Details of a Researcher - Takahashi, Masaki

Papers - Takahashi, Masaki

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Estimation of Three-Dimensional Ground Reaction Forces During Walking and Turning Using Insole Pressure Sensors Based on Gait Pattern Recognition

Eguchi R., Takahashi M.

IEEE Sensors Journal (IEEE Sensors Journal) 23 ( 24 ) 31278 - 31286 2023.12

ISSN 1530437X

Three-dimensional ground reaction forces (3D GRFs) in various gait patterns (e.g., walking and turning) provide essential information for clinical assessment. Previous scholars proposed to estimate GRFs from insoles with few pressure sensors using machine learning techniques. However, estimating GRFs during turning using a model learned from walking proved difficult because relationships between plantar pressure and GRFs vary according to the gait pattern. In this study, GRFs were estimated based on gait pattern recognition. GRF estimation models were learned from various gait patterns in advance. These models represented relationships between the insole measurements and GRFs using a Gaussian process regression (GPR). The GRFs were estimated from the insole measurements using a maximum likelihood (ML) model recognized as the current gait pattern. The ML model had the largest time frames, in which its standard deviation (SD) of the probabilistically estimated vertical GRF was the smallest among all the models (i.e., its training data were closest to the inputs), in the initial and terminal stance phases (subphases). In addition, the time frames of the contralateral leg were considered to enhance the recognition accuracy based on interlimb coordination. Experiment results showed that the proposed system, which used a common model learned from all the gait patterns for the vertical GRF and the ML model in the subphases of both legs for the horizontal GRFs, estimated 3D GRFs during walking and turning with different curvatures and directions with higher accuracy. The system can be widely applied for clinical walking tests and monitoring in daily life.

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Gait Measurement System Utilizing Missing Point Clouds Caused by Feet With Apple LiDAR Camera

Takahashi M., Takahashi M.

IEEE Sensors Letters (IEEE Sensors Letters) 7 ( 10 ) 2023.10

Gait measurement in clinical settings is often limited to qualitative evaluations despite the availability of various measurement devices. Although marker-less motion capture techniques, such as Kinect, have been attracting attention recently, they have rarely been introduced in the field because of the complexity of measurement operations. Therefore, in this letter, we propose a gait measurement algorithm that uses the light detection and ranging (LiDAR) camera of an iPad, a widely used mobile device. First, as part of the floor was hidden by the walking foot, the missing points in the floor point cloud were detected as feet. Subsequently, we placed the potentials at the detected foot positions, summed them over a series of frames, and obtained the local maximum value to obtain the ground position during walking. Spatial gait parameters, such as step length and width, were obtained from the ground position. In an accuracy verification experiment with 13 elderly subjects, the average absolute error of the step length was 28 mm, and that of the step width was 19 mm. These results indicated that the values estimated using the proposed method are useful for evaluating clinical tasks.

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Simultaneous Measurement of Respiratory and Pulse Information Using a Patch-Type Sensor for Sleep Apnea Hypopnea Detection

Ota Y., Yoshida T., Nagaoka H., Takahashi M.

IEEE Sensors Letters (IEEE Sensors Letters) 7 ( 10 ) 2023.10

Sleep apnea hypopnea syndrome (SAHS) is one of the most common sleeping disorders. However, numerous people suffering from SAHS are left undiagnosed. SAHS causes arousal reactions, sleep fragmentation, and hypoxemia, thus leading to excessive daytime sleepiness, lack of concentration, and a high risk of cardiovascular complications. Although polysomnography is the standard way of SAHS screening, its high cost, limited accessibility, and requirement of operational skills hinder its applicability for SAHS diagnoses. Therefore, this letter proposes a novel approach for SAHS detection using a patch-type photoplethysmography sensor. As an initial study, both respiratory and pulse information are simultaneously measured, and the trend of pulse variation, which reportedly has a strong correlation to oxygen saturation (SpO2), is thereby clarified. In addition, more real-time measurement of the pulse rate was possible on the chest compared to the fingertip. SAHS detection by incorporating respiratory and pulse information is beneficial for complete and credible screening and risk assessment of cardiovascular complications with less invasive devices. Therefore, this simple patch-type sensor can replace invasive, expensive, and limiting screening methods to facilitate the diagnosis of SAHS.

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The modeling and analysis for the natural frequency adjustments of Vehicle Manipulator for the ITER Blanket Remote Handling System

Tomoyuki I., Yuto N., Nobukazu T., Masaki T.

Fusion Engineering and Design (Fusion Engineering and Design) 192 2023.07

ISSN 09203796

This paper describes a method to adjust the natural frequency of the Vehicle Manipulator of the ITER Blanket Remote Handling System (BRHS). The natural frequency was adjusted to avoid the seismic resonance by using the redundancy of degree of freedom of the Vehicle Manipulator. The Vehicle Manipulator was modeled and analyzed with lumped mass model with joint stiffness. The analysis has shown that the natural frequencies of the Vehicle Manipulator can be changed from 0.5 Hz to 12 Hz in the gripping posture of the First Wall in the vacuum vessel, suggesting that the dominant seismic frequency around 7Hz-9 Hz can be avoided.

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Goal Inference via Corrective Path Demonstration for Human-Robot Collaboration

Ohnishi F., Kawasaki Y., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 577 LNNS 15 - 28 2023

ISSN 23673370

Recently, collaborative robots, such as collaborative delivery robots, have been expected to improve the work efficiency of users. For natural human-robot collaboration, it is necessary to infer the appropriate goal position to transport instruments, where the user’s convenience and the surrounding environment are considered. In conventional research, the goal is inferred by demonstrating the user’s desired positions, but position demonstration requires many trials to obtain the inference model, which is burdensome for the user. Therefore, we focus on the user’s correction of the robot position and generate multiple position samples from the user’s corrective path. In addition, these position samples are weighted based on the implicit intention of the correction to learn both the desired and undesired positions. Consequently, the robot improves goal inference in fewer trials. The effectiveness of the proposed method was evaluated by experiment that simulated human-robot collaborative environments.

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Switching Head-Tail Funnel UNITER for Dual Referring Expression Comprehension with Fetch-and-Carry Tasks

Korekata R., Kambara M., Yoshida Y., Ishikawa S., Kawasaki Y., Takahashi M., Sugiura K.

IEEE International Conference on Intelligent Robots and Systems (IEEE International Conference on Intelligent Robots and Systems) 3865 - 3872 2023

ISSN 21530858

This paper describes a domestic service robot (DSR) that fetches everyday objects and carries them to specified destinations according to free-form natural language instructions. Given an instruction such as 'Move the bottle on the left side of the plate to the empty chair,' the DSR is expected to identify the bottle and the chair from multiple candidates in the environment and carry the target object to the destination. Most of the existing multimodal language understanding methods are impractical in terms of computational complexity because they require inferences for all combinations of target object candidates and destination candidates. We propose Switching Head-Tail Funnel UNITER, which solves the task by predicting the target object and the destination individually using a single model. Our method is validated on a dataset based on a standard dataset for Vision-and-Language Navigation with object manipulation tasks. The results show that our method outperforms the baseline method in terms of language comprehension accuracy. Furthermore, we conduct physical experiments in which a DSR delivers standardized everyday objects in a standardized domestic environment as requested by instructions with referring expressions. The experimental results show that the object grasping and placing actions are achieved with success rates of more than 90 %.

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Rush-Out Risk Mapping from Human Operational Commands Considering Field Context<sup>∗</sup>

Ohnishi F., Kawasaki Y., Takahashi M.

IEEE International Workshop on Robot and Human Communication, RO-MAN (IEEE International Workshop on Robot and Human Communication, RO-MAN) 1196 - 1201 2023

ISSN 19449445

Collaborative delivery robots in hospitals are required to move safely and efficiently in a short time, without colliding with people. Hence, they must consider the risk of people rushing out from blind spots or rooms, including field context such as the role and usage of the location. However, these factors are difficult to extract solely from geometric information. Therefore, we propose a method for generating a rush-out risk map considering the field context from the hospital staf's operation data of an electric wheelchair. We convert the wheelchair's speed operated by staff into rush-out risk, and then place rush-out risk potentials at positions where rush-outs may occur. Subsequently, we optimize the mapping position of rush-out risk and parameters of each potential to minimize the error to obtain a rush-out risk map. We collected actual staff operation data in the hospital and confirmed that we could generate a rush-out risk map with small errors.

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Physics-Based Motion Planning of a Fruit Harvesting Manipulator for Pushing Obstacles in a Cluttered Environment

Nakamura M., Kawasaki Y., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 577 LNNS 204 - 215 2023

ISSN 23673370

Recently, the agricultural population is decreasing, and the demand for autonomous agricultural robots has increased. For a robot to successfully harvest fruits in diverse environments, various obstacles must be pushed away from its path. During the pushing motion, however, gravity acts on the fruits, causing them to move back and forth and return to their original state after being pushed away. This results in fruit-to-fruit contact, and fruit damage may occur. Therefore, a method to avoid obstacles while reducing the risk of fruit damage is required. However, the direct consideration of fruit damage is difficult because it requires many parameters that are difficult to observe. Herein, we propose a motion planning method by considering the potential energy of fruits as an evaluation index, which could be calculated based on observable parameters; this consideration could also suppress the reciprocating motion of fruits, thus preventing fruit damage. The proposed method was evaluated through simulations, and its effectiveness was verified.

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Multi-Agent Action Graph Based Task Allocation and Path Planning Considering Changes in Environment

Okubo T., Takahashi M.

IEEE Access (IEEE Access) 11 21160 - 21175 2023

Task allocation and path planning considering changes in the mobility of robots in the environment allows the robots to efficiently execute tasks with smaller travel times. A lunar base construction is one of the situations in which robots can more efficiently accomplish its goal by taking such environment changes into account when performing tasks. For the construction, we assumed that when a robot executes a task of building a road, the environment changes such that aisles that were unusable before the task become usable post execution. If such changes in environment are considered in advance, the robot can efficiently plan to wait until the environment changes and can move before executing the task. However, previous studies have not considered such changes, resulting in inefficient planning. To solve this problem, we developed a multi-agent action graph that consists of multiple layers and expresses the environment changes associated with task execution in terms of changes in these layers. In this graph, task allocation and path planning are formulated as a combinatorial optimization problem and are optimized using mixed-integer programming. Multi-agent action graphs and the proposed formulation enable efficient planning considering changes in the robots' mobility in advance. Through simulations, we confirmed that the proposed method completed the construction of the lunar base approximately 16.4% earlier than the conventional method, while consuming approximately 16.0% less total energy of the robots.

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Modeling of Body Pressure Distribution on Alternative Pressure Mattress

Kosuge M., Takahashi M.

2023 9th International Conference on Automation, Robotics and Applications, ICARA 2023 (2023 9th International Conference on Automation, Robotics and Applications, ICARA 2023) 289 - 293 2023

Recently, an alternative pressure mattress has been proposed to prevent pressure ulcers. In this study, we aim to design a control system for body pressure distribution using the mattress. This study focuses on modeling the dynamics between the body pressure distribution and the mattress. As modeling based on first principles is challenging, we identify the model from experimental data. However, when high-dimensional data such as body pressure distribution are directly used for identification, the model accuracy can deteriorate. Therefore, we need to determine the suitable model structure or dataset. Herein, we examined how the prediction accuracy of body pressure distribution varies with the dataset and model structure. We also proposed a method for representing the model as the dynamics of the parameters of the Gaussian Mixture Model to suppress the estimated parameters. To the best of our knowledge, this study is the first to propose the body pressure model as dynamics of the parameters of the Gaussian Mixture Model.

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Learning User-Preferred Robot Navigation Based on Social Force Model from Human Feedback in Virtual Reality Environments

Nakaoka S., Kawasaki Y., Takahashi M.

IEEE International Workshop on Robot and Human Communication, RO-MAN (IEEE International Workshop on Robot and Human Communication, RO-MAN) 1182 - 1187 2023

ISSN 19449445

Autonomous service robots are increasingly necessary to move without impeding the movement of pedestrians. Previous studies have determined optimal input for robots by minimizing a multi-objective function that includes the cost of reaching the destination and avoiding surrounding pedestrians. However, it is challenging to adjust the weights of each term in the cost function since they depend on the users and environment. In this study, we used the Social Force Model (SFM) as the base cost function and proposed a method to estimate SFM weights preferred by general user based on population density from human feedback. To achieve this, first we use Bayesian optimization and derive each user's evaluation map of SFM in a virtual reality environment that provides a realistic and immersive experience for subjects to provide feedback on the robot's movement. Second, we aggregated each user's evaluation map to estimate a general user's evaluation map. Finally, we have derived a functional relationship between the preferred SFM weights of general users and population density by Gaussian process regression. This relationship empowers the robot to navigate in a manner preferred by the general public, contingent on population density, even in the absence of human feedback obtained through virtual reality experimentation.

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Image-based robot navigation with task achievability

Ishihara Y., Takahashi M.

Frontiers in Robotics and AI (Frontiers in Robotics and AI) 10 2023

Image-based robot action planning is becoming an active area of research owing to recent advances in deep learning. To evaluate and execute robot actions, recently proposed approaches require the estimation of the optimal cost-minimizing path, such as the shortest distance or time, between two states. To estimate the cost, parametric models consisting of deep neural networks are widely used. However, such parametric models require large amounts of correctly labeled data to accurately estimate the cost. In real robotic tasks, collecting such data is not always feasible, and the robot itself may require collecting it. In this study, we empirically show that when a model is trained with data autonomously collected by a robot, the estimation of such parametric models could be inaccurate to perform a task. Specifically, the higher the maximum predicted distance, the more inaccurate the estimation, and the robot fails navigating in the environment. To overcome this issue, we propose an alternative metric, “task achievability” (TA), which is defined as the probability that a robot will reach a goal state within a specified number of timesteps. Compared to the training of optimal cost estimator, TA can use both optimal and non-optimal trajectories in the training dataset to train, which leads to a stable estimation. We demonstrate the effectiveness of TA through robot navigation experiments in an environment resembling a real living room. We show that TA-based navigation succeeds in navigating a robot to different target positions, even when conventional cost estimator-based navigation fails.

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Identification of Early Knee Osteoarthritis Based on Knee Joint Trajectory during Stair Climbing

Ogawa A., Iijima H., Takahashi M.

International Journal of Environmental Research and Public Health (International Journal of Environmental Research and Public Health) 19 ( 22 ) 2022.11

ISSN 16617827

Patients with knee osteoarthritis show low stair climbing ability, but a diagnosis of stair performance time is not enough to identify the early stages of knee osteoarthritis. Therefore, we developed an indicator named range of the knee joint trajectory (RKJT) as a kinematic parameter to express more detailed characteristics than stair performance time. To achieve this, we used our developed “IR-Locomotion”, a markerless measurement system that can track the knee joint trajectory when climbing stairs. This study aimed to test whether the RKJT effectively identifies patients with early knee osteoarthritis even after controlling stair performance time. Forty-seven adults with moderate to severe knee pain (mean age 59.2 years; 68.1% women) underwent the radiographic examination (Kellgren and Lawrence grade) of both knees and a stair climbing test on 11 stairs. The RKJT during the stair climbing test was calculated by “IR-Locomotion”. A generalized linear mixed model was used to evaluate the discriminative capability of RKJT on early knee osteoarthritis (i.e., Kellgren and Lawrence grade of 1). As expected, patients with early knee osteoarthritis showed larger RKJT than non-radiographic controls (95% confidence interval: 1.007, 1.076). Notably, this finding was consistent even after adjusting stair performance time.

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Decision-Making Based on Reinforcement Learning and Model Predictive Control Considering Space Generation for Highway On-Ramp Merging

Kimura H., Takahashi M., Nishiwaki K., Iezawa M.

IFAC-PapersOnLine (IFAC-PapersOnLine) 55 ( 27 ) 241 - 246 2022.09

Reducing traffic accidents pertaining to autonomous vehicles has garnered attention. Merging on a highway is one of the most challenging problems that must be addressed for the realization of autonomous vehicles. It is difficult because an agent must decide where to merge in a complex and ever-changing environment. Merging with congested highway traffic involves significant interaction with vehicles in the main lane. If there is no space for the autonomous vehicle to merge, it needs to work on vehicles in the main lane to create space and subsequently decide to merge or not. Reinforcement learning (RL) is a promising method for solving decision-making problems. However, it is difficult to guarantee the safety of the controller obtained using RL. Therefore, we propose a combined method in which decision-making is performed by RL and vehicle control by model predictive control (MPC) to ensure safety. The performance of the proposed system is tested by simulations. The proposed system made appropriate decisions according to the situation, and by controlling the vehicle in consideration of collision avoidance constraints, it showed a high merge success rate evenin a crowded situation.

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Time-constrained Optimization of Sit-to-stand Movements in Contact with the Environment

Inoue Y., Takahashi M.

IFAC-PapersOnLine (IFAC-PapersOnLine) 55 ( 27 ) 358 - 363 2022.09

This study aims to evaluate effects of different lower limb joint torque constraints on the motion trajectory of an sit-to-stand movement (STS) grasping an assistive device by simulating the STS with an assistive device using a human model with different lower limb joint torque constraints at various second lengths. This is an initial study for estimating lower limb muscle strength from the motion trajectory of the STS grasping an assistive device. In this study, instead of measuring many human subjects, optimal motion trajectories are calculated and simulated. Equations of the STS using the assistive device are first established using a rigid link model with both hands grasping the assistive device. Then, equations of motion and physical constraints such as joint range of motion and torque limitations are used as constraint conditions, and the sum of squares of joint torque, which calculates the action with the minimum muscle load on the body, is used as an evaluation function to optimize the STS. During optimization, calculations are performed with several types of joint torque conditions and end-time, i.e., the time required to complete the operation. By comparing several types of joint torque condition movements, the differences in the effects of different joint torque constraints on the motion trajectory of the STS grasping the assistive device can be determined.

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Analysis of Spastic Gait in Patients with Cervical Myelopathy Using the Timed up and Go Test with a Laser Range Sensor

Koyama T., Fujita K., Iijima H., Norose M., Ibara T., Sasaki T., Yoshii T., Nimura A., Takahashi M., Okawa A.

Spine (Spine) 47 ( 12 ) 892 - 898 2022.06

ISSN 03622436

Study Design. Cross-sectional study. Objective. This study aimed to objectively evaluate spastic gait and reveal its novel characteristics via analysis of gait in patients with cervical myelopathy (CM) using the Timed Up and Go (TUG) test with a laser range sensor. Summary of Background Data. Among patients with CM, spastic gait is a common diagnostic symptom; thus, objective assessments of spastic gait would be useful for the diagnosis of CM and recognition of disease status. Although spastic gait has been objectively evaluated in previous studies, the methods employed in those studies are not suitable for clinical settings. Methods. In total, 37 and 24 participants were recruited for a control group and CM group, respectively. CM was diagnosed by spine surgeons. We developed a laser TUG test, in which the position and velocity of both the legs were captured. The parameter values for both groups were statistically compared, and odds ratios were calculated using logistic regression analyses. Results. The total TUG-test time, time to stand up, time to first step, number of steps, and trajectory error for the CM group were significantly higher than those for the control group, whereas the average velocity and average stride length for the CM group were significantly lower than those for the control group. There was a significant independent association between the total TUG-test time and CM. The optimal cutoff point of the total test time for CM risk was approximately 9seconds. Conclusion. Through the use of the laser TUG test, we were able to identify characteristics of spastic gait, which leads to difficulty in standing and taking the first step, wobbling while walking, and an increased risk of falling. We found that the risk of CM was higher if the individual took longer than 9seconds to complete the TUG test.

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Empirical study of future image prediction for image-based mobile robot navigation

Ishihara Y., Takahashi M.

Robotics and Autonomous Systems (Robotics and Autonomous Systems) 150 2022.04

ISSN 09218890

Recent image-based robotic systems use predicted future state images to control robots. Therefore, the prediction accuracy of the future state image affects the performance of the robot. To predict images, most previous studies assume that the camera captures the entire scene and that the environment is static. However, in real robot applications, these assumptions do not always hold. For example, if a camera is attached to a mobile robot, its view changes from time to time. In this study, we analyzed the relationship between the performance of the image prediction model and the robot's behavior, controlled by an image-based navigation algorithm. Through mobile robot navigation experiments using front-faced and omni-directional cameras, we discussed the capabilities of the image prediction models and demonstrated their performance when applied to the image-based navigation algorithm. Moreover, to adapt to the dynamic changes in the environment, we studied the effectiveness of directing the camera to the ceiling. We showed that robust navigation can be achieved without using images from cameras directed toward the front or the floor, because these views can be disturbed by moving objects in a dynamic environment.

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Human Leg Tracking by Fusion of Laser Range and Insole Force Sensing With Gaussian Mixture Model-Based Occlusion Compensation

Eguchi R., Takahashi M.

IEEE Sensors Journal (IEEE Sensors Journal) 22 ( 4 ) 3704 - 3714 2022.02

ISSN 1530437X

Simultaneous measurement of spatial, temporal, and kinetic gait parameters has become important for monitoring patients with neurological disorders in a hospital. As spatial sensing technologies, laser range sensors (LRSs), which obtain highly accurate two-dimensional distance data over a wide range, have been employed to detect/track both legs during walking. However, when walking on curved trajectories, a continuous occlusion occurs over several sampling steps and produces false tracking. To address this issue in combination with temporal and kinetic sensing, this paper presents a fusion system of LRSs and force-sensing insoles and an occlusion compensation based on probabilistic motion models. First, the system pre-tracks a target person during walking along a straight line and curved paths under different curvatures/directions in a situation without occlusion. Gait cycles of each walking type are divided by foot-grounding obtained from the insoles. Relationships between leg trajectories and traveling directions during the gait cycle are then learned using user-specific Gaussian mixture models (GMMs). When an occlusion occurs in post-tracking, a maximum likelihood (ML) GMM is identified using a joint probability of both legs' trajectories, in accordance with biomechanics that both legs move in a coordinated manner. The ML GMM then compensates for the traveling direction and position of the occluded leg, and the system interpolates/re-tracks its positions to correct the states during occlusion. Experimental results demonstrated that the proposed method (fusion with the insoles, occlusion compensation, and interpolation/re-tracking) significantly enhanced tracking performance during occlusion and estimated leg positions with valid accuracy (errors of under 60 mm).

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Dynamic Object Removal from Unpaired Images for Agricultural Autonomous Robots

Akada H., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 412 LNNS 641 - 653 2022

ISSN 23673370

Recently, the demand for agricultural autonomous robots has been increasing. Using the technology of vision-based robotic environmental recognition, they can generally follow farmers to support their work activities, such as conveyance of the harvest. However, a major issue arises in that dynamic objects (including humans) often enter images that the robots rely on for environmental recognition tasks. These dynamic objects degrade the performance of image recognition considerably, resulting in collisions with crops or ridges when the robots are following the worker. To address the occlusion issue, generative adversarial network (GAN) solutions can be adopted as they feature a generative capability to reconstruct the area behind dynamic objects. However, precedented GAN methods basically presuppose paired image datasets to train their networks, which are difficult to prepare. Therefore, a method based on unpaired image datasets is desirable in real-world environments, such as a farm. For this purpose, we propose a new approach by integrating the state-of-the-art neural network architecture, CycleGAN, and Mask R CNN. Our system is trained with a human-tracking dataset collected by an agricultural autonomous robot in a farm. We evaluate the performance of our system both qualitatively and quantitatively for the task of human removal in images.

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Future Image Prediction for Mobile Robot Navigation: Front-Facing Camera Versus Omni-Directional Camera

Ishihara Y., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 412 LNNS 654 - 669 2022

ISSN 23673370

When we perform a task, we select the action by imagining its future consequences. Hence, the ability to predict future states would also be an essential feature for robotic agents because it would allow them to plan effective actions to accomplish given tasks. In this research, we explore an action-conditioned future image prediction model considering its application to navigation tasks for a mobile robot. We investigate the image prediction performance of deep neural network architectures and training strategies with two different camera systems. One camera system is a conventional front-facing camera that has a narrow field of view with high definition, and the other is an omni-directional camera that has a wide field of view with low definition. We compare the performances of prediction models for these two camera systems, and propose using an image prediction model with the omni-directional camera for the navigation tasks of a robot. We evaluate the prediction performance of each camera system through experiments conducted in a complex living room-like environment. We demonstrate that models with an omni-directional camera system outperform models with a conventional front-facing camera. In particular, the model comprising a combination of action-conditioned long short-term memory successfully predicts future images for states of more than 100 steps ahead in both simulation and real-world scenarios. Further, by integrating the proposed system into image-prediction-based navigation algorithm, we demonstrate that navigation based on a model with an omni-directional camera can successfully navigate the robot in cases where one with a conventional front-facing camera fails.

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Harmonious Robot Navigation Strategies for Pedestrians

Nakaoka S., Yorozu A., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 412 LNNS 98 - 108 2022

ISSN 23673370

Recently, the demand for service robots that move autonomously in a crowded environment, such as stations, airports, and commercial facilities has increased. Such robots are required to move to a destination without hindering the progress of the surrounding pedestrians. Previous papers proposed collision avoidance methods based on the direction and distance of the destination of the robot, and the position and velocity of pedestrians in the vicinity. However, in a crowded environment, the behavior of a robot may affect other pedestrians, or the behavior of a pedestrian facing the robot may affect other pedestrians. Moreover, considering the motion strategy used by a pedestrian in a crowded environment, the impact on other pedestrians can be reduced by the robot following the pedestrians moving in the direction in which the robot wants to move. This navigation method has not been proposed thus far. Therefore, in this paper, we propose a method that considers the impact of the robot on surrounding pedestrians and the impact of those pedestrians on other pedestrians. The robot determines the avoidance or following action based on the traveling direction of the surrounding pedestrians.

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Human-Following Control in Furrow For Agricultural Support Robot

Yorozu A., Ishigami G., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 412 LNNS 155 - 164 2022

ISSN 23673370

In Japan, the reduction in agricultural work population and increase in abandoned cultivated land are major social issues. To overcome these issues, we have proposed a small agricultural robot that supports the transportation of harvested crops while it follows the user. To move in the furrowed field, ridges and furrows where the robot can move must be detected using robot-mounted sensors and follow the ridge while avoiding the ridges and crop rows. However, when the robot follows the user ahead of it, it has difficulty detecting the ridges because of occlusion by the user. In addition, the robot requires to follow the user and move in and out of furrows of different widths in the farm field. To achieve smooth and safe harvesting support in the field with different width furrows, we propose a method for ridge detection and tracking by measuring the furrow width and interpolation using an RGB-D camera and a method for human-following control while avoiding ridges according to the ridge observation state using fuzzy set theory. To verify the proposed methods, experiments in the farm are carried out.

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Introduction of Damping Control for Obstacle Avoidance in Direct-Contact Cobotics Operations

Huart A., Yorozu A., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 412 LNNS 506 - 517 2022

ISSN 23673370

In this study, obstacle avoidance in the collaborative robotics field, where a human operator moves the robot manually through direct contact, is investigated. If an operator is distracted or is not used to control the robot, an accident can happen during operation, which might harm the operator. For the purpose of assisting the human operator in his/her task, the integration of a damping control is proposed. Damping is a coefficient that influences the oscillations of a system. By modifying the damping of the robot, an artificial stiffness is created. The information is transmitted to the user through his/her haptic return, making it easier for him/her to avoid the obstacles in the workspace. In this study, a damping control is developed and implemented. Then, through experimentation, the efficiency of the haptic sense and the general damping control are demonstrated, and thus, an efficient, comfortable, and safe method is formulated for the operator to avoid obstacles during operations.

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Mobile Robot Localization Considering the Attributes of Objects to Prevent the Kidnapped Robot Problem

Harada T., Yorozu A., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 412 LNNS 41 - 53 2022

ISSN 23673370

To prevent the occurrence of the kidnapped robot problem, it is vital to evaluate the likelihood of each particle considering an environmental change. Moving objects are one of the leading causes of environmental change, and each object has its own movability. For example, a chair has high movability because it is designed to move and often interacts with humans. However, walls or shelves have low movability because they are designed not to move, and they interact less often with humans. Therefore, in this study, we define classes of objects and their movability. We propose a localization approach that focuses on the association between sensor information obtained from objects whose movability is low and prior map by considering classes and movability, to prevent the occurrence of the kidnapped robot problem.

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Topometric Navigation Considering Movable Objects

Mochizuki S., Yorozu A., Takahashi M.

Lecture Notes in Networks and Systems (Lecture Notes in Networks and Systems) 412 LNNS 87 - 97 2022

ISSN 23673370

Recently, the demand for mobile manipulator-type human support robots has been increasing. Human support robots recognize the surrounding environment using a previously generated environmental map and perform navigation, such as localization and path planning. Conventional environment maps do not consider characteristics of objects and do not have any option to move an object to clear a path making it difficult for robots to move efficiently when an object is placed on their path. In this study, we propose topological navigation that uses a topological map based on sensing information and representing a path that robots can pass, and a metric map based on geometrical information of objects and representing the presence of objects. Consequently, if necessary, it is possible for robots to move a movable object to clear the passage and realize efficient movement in living environments.

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PROPOSAL OF AMD CONTROL METHOD BASED ON MODEL PREDICTIVE CONTROL FOR BMD VIBRATION CONTROL STRUCTURE AND VERIFICATION WITH SHAKING TABLE TEST

Yoshida N., Kotsuki S., Morikawa K., Kambara H., Fukukita A., Takahashi M.

Journal of Structural and Construction Engineering (Journal of Structural and Construction Engineering) 87 ( 798 ) 701 - 712 2022

ISSN 13404202

This paper proposes a control method of Active Mass Damper (AMD) for Building Mass Damper (BMD). The parameters of the soft story of BMD must be higher than the optimal values to prevent excessive displacement of the soft story. The AMD makes the behavior of the non-optimal BMD close to that of the optimal BMD and improves damping performance by the proposed control method, which is based on Model Predictive Control (MPC). Through the results of numerical analysis and shaking table test, it is demonstrated that the proposed method can mitigate the responses of the non-optimal BMD.

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World State-dependent Action Graph: A Representation of Action Possibility and Its Variations in Real Space based on World State

Kawasaki Y., Takahashi M.

Proceedings of the International Conference on Informatics in Control, Automation and Robotics (Proceedings of the International Conference on Informatics in Control, Automation and Robotics) 1 459 - 466 2022

ISSN 21842809

For intelligent systems, it is important to understand the action possibility for agent in real space. As the action possibility varies with the subsystem configuration of the agent and its states, the possibilities should be understood based on the world state comprising the agent’s state as well as the environmental state. However, most conventional methods consider only the environmental state. Therefore, this study proposes a world state-dependent action graph based on knowledge representation using scene graphs which allows the capturing of the action possibility of agents, which implies the feasible actions and their positions in real space, and their recursive variations depending on the world state. Moreover, the effectiveness of the proposed method was verified with simulations, assuming a coffee shop environment.

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UnrealEgo: A New Dataset for Robust Egocentric 3D Human Motion Capture

Akada H., Wang J., Shimada S., Takahashi M., Theobalt C., Golyanik V.

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)) 13666 LNCS 1 - 17 2022

ISSN 03029743

We present UnrealEgo, i.e., a new large-scale naturalistic dataset for egocentric 3D human pose estimation. UnrealEgo is based on an advanced concept of eyeglasses equipped with two fisheye cameras that can be used in unconstrained environments. We design their virtual prototype and attach them to 3D human models for stereo view capture. We next generate a large corpus of human motions. As a consequence, UnrealEgo is the first dataset to provide in-the-wild stereo images with the largest variety of motions among existing egocentric datasets. Furthermore, we propose a new benchmark method with a simple but effective idea of devising a 2D keypoint estimation module for stereo inputs to improve 3D human pose estimation. The extensive experiments show that our approach outperforms the previous state-of-the-art methods qualitatively and quantitatively. UnrealEgo and our source codes are available on our project web page (https://4dqv.mpi-inf.mpg.de/UnrealEgo/ ).

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Spatio-Temporal Action Order Representation for Mobile Manipulation Planning

Kawasaki Y., Takahashi M.

RO-MAN 2022 - 31st IEEE International Conference on Robot and Human Interactive Communication: Social, Asocial, and Antisocial Robots (RO-MAN 2022 - 31st IEEE International Conference on Robot and Human Interactive Communication: Social, Asocial, and Antisocial Robots) 1093 - 1098 2022

Social robots are used to perform mobile manipulation tasks, such as tidying up and carrying, based on instructions provided by humans. A mobile manipulation planner, which is used to exploit the robot's functions, requires a better understanding of the feasible actions in real space based on the robot's subsystem configuration and the object placement in the environment. This study aims to realize a mobile manipulation planner considering the world state, which consists of the robot state (subsystem configuration and their state) required to exploit the robot's functions. In this paper, this study proposes a novel environmental representation called a world state-dependent action graph (WDAG). The WDAG represents the spatial and temporal order of feasible actions based on the world state by adopting the knowledge representation with scene graphs and a recursive multilayered graph structure. The study also proposes a mobile manipulation planning method using the WDAG. The planner enables the derivation of many effective action sequences to accomplish the given tasks based on an exhaustive understanding of the spatial and temporal connections of actions. The effectiveness of the proposed method is evaluated through practical machine experiments performed. The experimental result demonstrates that the proposed method facilitates the effective utilization of the robot's functions.

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Space Lander Descent Control System Design Considering Fuel Sloshing Under Microgravity

Tanaka Y., Baba M., Otsuki M., Fujita K., Himeno T., Maeda T., Takahashi M.

Proceedings of the IEEE Conference on Decision and Control (Proceedings of the IEEE Conference on Decision and Control) 2022-December 3092 - 3097 2022

ISSN 07431546

This study proposes a descent control system for a space lander with a large amount of fuel, to protect the lander from overturning when landing on microgravity objects. As sloshing is a major problem during descent, it is desirable to construct a control system that considers the sloshing dynamics. We derive a model of the lander considering fuel dynamics, determine the fuel-optimal trajectory for guidance, design a fuel state estimator for navigation, and design a tracking controller. The effectiveness of the proposed method is evaluated using a physical simulator. The proposed method achieves simultaneous stabilization of the lander and fuel, and is shown to be effective in preventing overturning.

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Simultaneous Optimization of Task Allocation and Path Planning Using Mixed-Integer Programming for Time and Capacity Constrained Multi-Agent Pickup and Delivery

Okubo T., Takahashi M.

International Conference on Control, Automation and Systems (International Conference on Control, Automation and Systems) 2022-November 1088 - 1093 2022

ISSN 15987833

Lately, there has been a need to improve the efficiency of material movements within factories and multi-agents are required to perform these tasks. In this study, graphical representation and mixed-integer programming have been adopted for simultaneous optimization of task allocation and path planning for each agent to achieve the following three goals. First, this study realizes time and capacity constrained multi-agent pickup and delivery (TCMAPD) that simultaneously considers time constraints, capacity constraints, and collision avoidance. Previous studies have not considered these constraints simultaneously. Thus, we can solve the problems associated with using multi-agents in actual factories. Second, we achieved TCMAPD that optimizes the collision avoidance between multi-agents. In conventional research, only a single collision avoidance method can be used. However, an appropriate route was selected from a variety of avoidance methods in this study. Hence, we could achieve a more efficient task allocation and path planning with collision avoidance. Third, the proposed method simultaneously optimizes task allocation and path planning for each agent. Previous studies have separately considered the approach of optimizing task allocation and path planning or used the cost of path planning after task allocation to again perform task allocation and path planning. To simultaneously optimize them in a single plan, we have developed a solution-derivable formulation using mixed-integer programming to derive a globally optimal solution. This enables efficient planning with a reduced total time traveled by the agents.

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ProTAMP: Probabilistic Task and Motion Planning Considering Human Action for Harmonious Collaboration

Mochizuki S., Kawasaki Y., Takahashi M.

IEEE International Conference on Intelligent Robots and Systems (IEEE International Conference on Intelligent Robots and Systems) 2022-October 2159 - 2166 2022

ISSN 21530858

For the proper functioning of mobile manipulator-type autonomous robot performing complicated tasks in a human-robot coexistence environment, tasks and motions must be planned simultaneously. In such environments, a human and robot should collaborate with each other. Therefore, the robot must act in accordance with the human and avoid useless actions duplicated with those of humans. However, any action undertaken by a human has uncertainty, and thus, predicting them correctly is challenging. This study proposed probabilistic task and motion planning considering both deterministic and probabilistic environment changes caused by robot and human actions temporarily and spatially, respectively. First, the environmental changes were modeled, where the robot is capable of recognizing the possibility of environmental changes. Second, in task planning, the probabilities of each environmental change owing to human actions was minimized. Finally, in motion planning, a movement path connecting each task in a planned order was planned, thereby enabling the robot to perform actions not duplicated with those by a human. Furthermore, the plans generated were compared without considering possibility of human actions and the effectiveness of the proposed method was verified. Consequently, the proposed method was confirmed to reduce the time required for finishing the tasks.

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Footsteps and walking trajectories during the Timed Up and Go test in young, older, and Parkinson's disease subjects

Okada Y., Yorozu A., Fukumoto T., Morioka S., Shomoto K., Aoyama T., Takahashi M.

Gait and Posture (Gait and Posture) 89 54 - 60 2021.09

ISSN 09666362

Background: Footsteps and walking trajectories during the Timed Up and Go test (TUG), and their relationships with spatiotemporal gait parameters during turning in people with Parkinson's disease (PD) and older people have not been clarified. Research question: We investigated the footsteps, walking trajectories, and spatiotemporal parameters during the TUG in PD, healthy older (HO), and healthy young (HY) subjects and the associations between the parameters of footsteps or walking trajectories and the spatiotemporal parameters during turning. Methods: Twenty-six PD, 20 HO, and 20 HY subjects participated. They performed the TUG at self-selected speed and underwent evaluations of spatiotemporal parameters in the forward, turning, and return phases and parameters of footsteps and walking trajectories by a system using laser range sensors to measure the two-dimensional distance data of the legs. Foot placement for each foot was measured as the estimated position when the leg speed of movement reached the minimum between foot-contact and foot-off. We calculated the minimum distance from a TUG marker to footsteps and the maximum anterior distance from the start to the footsteps. Step length was calculated using a method for non-linear walking. Results: The PD subjects showed significantly smaller step lengths in all phases. The minimum distance from the marker to the footsteps in PD subjects was significantly smaller than in HO subjects and was significantly positively correlated only with the turning-phase step length. The maximum anterior distance from the start to footsteps in HO subjects was significantly larger than in PD and HY subjects and was not correlated with any spatiotemporal parameters. Significance: This study demonstrated that people with PD turn close to the TUG marker, and this turning strategy may be associated with the decreased step length when turning. These findings could help in providing instructions which prevent the exaggeration of step-length reduction when turning.

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Image-based Action Generation Method using State Prediction and Cost Estimation Learning

Ishihara Y., Takahashi M.

Journal of Intelligent and Robotic Systems: Theory and Applications (Journal of Intelligent and Robotic Systems: Theory and Applications) 103 ( 1 ) 2021.09

ISSN 09210296

This study proposes an image-based action generation method using a controller that is trained with experiences autonomously collected by a robot. Operating a robot using its state or point in coordinate space is not always easy for human operators to control. This is because humans do not interpret the world as a coordinate space. Depending on the task, inputs such as voice-input or image-input are easier for human operators to use when managing a robot. Accordingly, we studied an image-based control method of robotic agents. Designing an image-based controller by hand for different tasks and input images is highly complex. Therefore, a controller which can be automatically trained from experiences collected by a robot is strongly preferred. In addition, when considering the operation of a robot in a real environment, the controller should guarantee the safety of a robot’s behavior in a way that is configurable and understandable by the human operator. However, most previous approaches trained the controller end-to-end, which does not guarantee the safety of the behavior learned by the controller. Instead of training the controller end-to-end, we train state prediction and cost estimation functions to solve the action generation as a path planning problem. By doing so, we can explicitly design and specify the undesired state of a robot in the configuration space. The results show that the proposed method can be used to provide safe navigation to different goal positions in a realistic living room-like environment with an hour of training data.

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Microcurrent Therapy as a Therapeutic Modality for Musculoskeletal Pain: A Systematic Review Accelerating the Translation From Clinical Trials to Patient Care

Iijima H., Takahashi M.

Archives of Rehabilitation Research and Clinical Translation (Archives of Rehabilitation Research and Clinical Translation) 3 ( 3 ) 2021.09

Objective: To summarize the level of knowledge regarding the effects of microcurrent therapy (MCT) on musculoskeletal pain in adults. Data Sources: The PubMed, Physiotherapy Evidence Database, Cumulative Index to Nursing Allied Health Literature, Cochrane Central Register of Controlled Trials, and Igaku Chuo Zasshi database were searched from the time of their inception to December 2020. Study Selection: Randomized controlled trials (RCTs) investigating the effects of MCT on musculoskeletal pain were included. Additionally, non-RCTs were included to assess the adverse events. Data Extraction: The primary outcomes were pain and adverse events related to MCT. To assess the reproducibility of MCT, we evaluated the completeness of treatment description using the Template for Intervention Description and Replication (TIDieR) checklist. We also assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Data Synthesis: A comprehensive assessment of 4 RCTs and 5 non-RCTs that met the inclusion criteria revealed that MCT significantly improved shoulder pain (1 study, 40 patients) and knee pain (1 study, 52 patients) compared with sham MCT without any severe adverse events. MCT has clinically significant benefits for knee pain. This study also revealed a clinically significant placebo response in treating knee pain. This evidence highlights the substantial effect of placebo response in clinical care. These treatment effects on knee pain are further supported by the high quality of evidence in GRADE with high reproducibility in TIDieR. Conclusions: The findings of this meta-analysis highlight the effect of placebo response in treating knee pain. MCT is a potential, core nonpharmacologic treatment option in clinical care with minimal adverse events and should be further investigated. This study proposes a framework for the future investigation of the effect of MCT on musculoskeletal pain to enhance the study quality and reproducibility.

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Staircase design for health monitoring in elderly people

Ogawa A., Iijima H., Takahashi M.

Journal of Building Engineering (Journal of Building Engineering) 37 2021.05

The need for early detection and intervention for age-related health deterioration via home-based health monitoring systems is growing with global population aging. Health deterioration is typically evaluated using questionnaires, but obtaining frequent responses is difficult. Although stair walking involving a high physical load is suitable for assessing health deterioration, uniform assessment using home-based systems is difficult because different stair designs result in different movements. There is currently insufficient research on differences in evaluation performance between different stair designs. The current study aimed to develop an objective index to assess difficulties in activities of daily living (ADLs) as an indicator of health deterioration by observing stair walking, and to investigate the effects of stair dimensions on the relationship between the index and health deterioration. We hypothesized that knee joint positions during stair ascent would be associated with health deterioration, and developed the “Stepping in Level” index, reflecting the knee joint position when stepping in, obtained using a markerless depth information-based system. Seventy elderly people ascended two types of stairs (steep: 33.7°; shallow: 28.2°) and completed a questionnaire regarding ADL difficulty. We used a generalized linear mixed model to investigate the ability of “Stepping in Level” to explain ADL difficulty. The results revealed that “Stepping in Level” was able to explain ADL difficulty, and steep stairs were more suitable than shallow stairs for assessment. Our system enables daily assessment of difficulty in ADLs and detection of subtle changes in daily life. The current findings could inform design guidelines for health monitoring.

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Low Back Pain as a Risk Factor for Recurrent Falls in People With Knee Osteoarthritis

Iijima H., Shimoura K., Aoyama T., Takahashi M.

Arthritis Care and Research (Arthritis Care and Research) 73 ( 3 ) 328 - 335 2021.03

ISSN 2151464X

Objective: Knee osteoarthritis (OA) has been suggested to increase the risk of falls. Low back pain (LBP) is a potential risk factor for falls in people with knee OA, but this issue has not been addressed adequately in previous studies. The objective of this study was to investigate the relationship between LBP and falls in people with knee OA in a 12-month period. Methods: Participants with knee OA (Kellgren/Lawrence [K/L] grade ≥1) completed questionnaires for LBP and falls that occurred in the preceding 12 months. Binary and ordinal logistic regression analyses were performed to assess the relationship between LBP or moderate-to-severe LBP (numeric rating scale ≥4 points) and any fall (≥1 fall) or recurrent falls (≥2 falls) after adjustment for age, sex, K/L grade, knee pain severity, and quadriceps strength. Sensitivity analyses were performed excluding people with sciatica, nonchronic LBP, K/L grade 1, and those receiving pain medications. Results: We included 189 participants (ages 61–90 years, 78.3% women) in this study. Of these participants, 41 (21.6%) reported falls in the preceding 12 months. People with any LBP (n = 101) and those with moderate-to-severe LBP (n = 45) had 2.7- and 3.7-times higher odds of recurrent falls, respectively. Sensitivity analyses revealed a strong correlation between moderate-to-severe LBP and recurrent falls. Conclusion: Thorough investigation of LBP as a risk factor for recurrent falls in people with knee OA may provide a novel insight into the pathomechanics of recurrent falls in this population.

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Crater detection robust to illumination and shape changes using convolutional neural network

Ishida T., Takahashi M., Fukuda S.

Transactions of the Japan Society for Aeronautical and Space Sciences (Transactions of the Japan Society for Aeronautical and Space Sciences) 64 ( 4 ) 197 - 204 2021

ISSN 05493811

As a vast amount of data with respect to the moon and Mars is collected, exploration missions are shifting to the next step, the aim of which is a precise landing on a predetermined target. A promising technology for precision landing is terrain relative navigation (TRN), which collates landmarks detected from images and maps of landmarks. Crater detection is one of the essential technologies for TRN. A problem in detecting craters is the apparent change in craters due to illumination conditions. Another problem is the change in shape due to crater degradation. We propose a novel crater detection method based on combining a support vector machine (SVM) and a convolutional neural network (CNN) to make detection performance robust against apparent change. In the linear SVM, gradient images of a crater image dataset are learned. The learned classifier is then used to calculate the objectness score for region proposal. Next, the CNN identifies the image of the proposed region as to whether or not it is a crater. Our results show that the proposed method can detect craters in a wide range of illumination and shape conditions, and has better average precision than traditional crater detectors.

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Uncertainty-aware Non-linear Model Predictive Control for Human-following Companion Robot

Sekiguchi S., Yorozu A., Kuno K., Okada M., Watanabe Y., Takahashi M.

Proceedings - IEEE International Conference on Robotics and Automation (Proceedings - IEEE International Conference on Robotics and Automation) 2021-May 8316 - 8322 2021

ISSN 10504729

For a companion robot that follows a person as an assistant, predicting human walking is important to produce a proactive movement that is helpful to maintain an appropriate area decided by the human personal space. However, fully trusting the prediction may result in obstructing human walking because it is not always accurate. Hence, we consider the estimation of uncertainty (i.e., entropy) of the prediction to enable the robot to move without causing overconfident motion and without being late for the person it follows. To consider this uncertainty of the prediction to the controller, we introduce a reliability value that changes based on the entropy of the prediction. This value expresses the extent the controller should trust the prediction result, and it affects the cost function of our controller. We propose an uncertainty-aware robot controller based on nonlinear model predictive control to realize natural human-followings. We found that our uncertainty-aware control system can produce an appropriate robot movement, such as not obstructing the human walking and avoiding delay, in both simulations using actual human walking data and real-robot experiments.

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Bottom-up action modeling via spatial factorization for serving food

Kawasaki Y., Takahashi M.

Advanced Robotics (Advanced Robotics) 35 ( 12 ) 756 - 770 2021

ISSN 01691864

The goal state of the robot motion involved in an action is determined by the action model based on the effect of the action and the scene state. This study focuses on serving food as a robot action; the action model of serving food is obtained based on demonstrations. The arrangement position is determined by considering the spatial relations between the object being served and the multiple selected reference objects. Therefore, it is necessary to learn the importance of the relations for the reference and the spatial relations between objects based on demonstrations. In this paper, bottom-up action modeling is proposed as an action modeling approach based on the demonstration. In this method, the spatial relations between labeled objects and the importance of the relations are learned through spatial factorization of the scene into partial relations. This approach enables the robot to determine the arrangement position intended by the demonstrator, even in unknown scenes. The effectiveness of the proposed method was evaluated by simulation, which the action of serving food.

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Body pressure prediction for pressure ulcer prevention in a bed head elevation operation

Kosuge M., Ishihara Y., Takahashi M.

Advanced Robotics (Advanced Robotics) 35 ( 3-4 ) 181 - 193 2021

ISSN 01691864

Pressure ulcers are caused by tissue damage, which occurs when the blood supply to an area of skin is diminished because of sustained or concentrated pressure on a patient from the mattresses of a bed. One action that concentrates the pressure is a bed head elevation operation. Recently, a control system known as the alternative pressure mattress has been proposed to prevent the concentration of pressure. However, the challenge with this controlled system is that it has a slow response because it uses air cells. The slow response causes controlling the air cells to lag behind the change in pressure during the bed head elevation operation. Therefore, this system cannot adequately prevent the concentration of pressure on a patient. To address this issue, we need to predict the change in pressure during the bed head elevation operation and control the pressure based on this prediction. In the current work, we focus on predicting the pressure distribution. This prediction is high-dimensional. We regarded the pressure distribution as an image and predicted the change in pressure by applying a deep neural network. To the best of our knowledge, this paper is the first to propose the body pressure predictive model.

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ASTRON: Action-Based Spatio-Temporal Robot Navigation

Kawasaki Y., Mochizuki S., Takahashi M.

IEEE Access (IEEE Access) 9 141709 - 141724 2021

To achieve the tasks provided by a user, it is necessary for robots to have a plan that fully exploits their functionalities in an environment. The objective of this study is to realize robot task planning in real space for effectively use of the robot's functions The plan is formed by deriving a feasible action sequence by interpreting the instructions within the scope of the action possibilities of the robots and the changes in them. In this paper, we first propose an action graph as a novel environmental representation approach to facilitate the understanding of the robot's action possibility in real space. In the action graph, the action possibility is represented by nodes, which describe the spatial position to perform each feasible action, and edges, which describe the feasible actions, based on the subsystem-level affordance and the arrangement of objects in the environment. We also propose an action-based spatio-temporal robot navigation (ASTRON), which focuses on robot navigation tasks. ASTRON enables the robots to determine a feasible action sequence that utilizes their functions by interpreting the instructions based on the action graph. The effectiveness of the proposed method was evaluated through simulations and actual machine experiments in a coffee shop environment. In the actual machine experiments, the proposed method was applied to robots with different subsystem configurations. The experimental results demonstrated that the proposed method could plan the feasible action sequence to complete the tasks by considering the environmental state and the subsystem configurations of the robot.

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Transcutaneous Electrical Nerve Stimulation Improves Stair Climbing Capacity in People with Knee Osteoarthritis

Iijima H., Eguchi R., Shimoura K., Yamada K., Aoyama T., Takahashi M.

Scientific Reports (Scientific Reports) 10 ( 1 ) 2020.12

© 2020, The Author(s). This study aimed to examine the effect of transcutaneous electrical nerve stimulation (TENS) on stair climbing capacity in individuals with pre-radiographic to mild knee osteoarthritis (OA). This is a secondary analysis of data from a single, participant-blinded, randomized controlled trial with a pre-post design. Participants with pre-radiographic to mild knee OA (mean age, 59.1 years; 72.9% women) were randomly assigned into two groups, a TENS (n = 30) and a sham-TENS groups (n = 29). TENS or sham-TENS treatments were applied to all participants by using the prototype TENS device with pre-specified parameters. The primary outcome measures included valid and reliable functional measures for stair climbing (stair-climb test [SCT]), visual analog scale for knee pain during the SCT, and quadriceps muscle strength. TENS improved SCT time by 0.41 s (95% confidence interval [CI]: 0.07, 0.75). The time reduction in the transition phase explains the TENS therapeutic effect. Post-hoc correlation analyses revealed a non-significant but positive relationship between the pain relief effect and improved 11-step SCT time in the TENS group but not in the sham-TENS group. These results indicate that the TENS intervention may be an option for reducing the burden of early-stage knee OA.

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Dynamic Motion Tracking Based on Point Cloud Matching with Personalized Body Segmentation

Ono T., Eguchi R., Takahashi M.

Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics (Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics) 2020-November 61 - 67 2020.11

ISSN 9781728159072

Falling is a serious problem with the growing elderly population. In this sense, clinical institutions have implemented motor function assessment programs. In particular, the timed up and go test (TUG) is the most frequently applied clinical trial to assess the elderly walking ability in many clinical institutions and communities. In this study, we proposed a gait measurement system that can evaluate motor function in dynamic gait tests, such as the TUG test, using the point clouds of depth sensors (Kinect). The TUG test is a dynamic task that includes 3m of walking and turning motion. However, estimating joint positions using conventional methods that use Kinect skeleton function or point clouds is difficult. To solve these problems, before applying the iterative closest point algorithm, we proposed a method to move the segment model to a pre-estimated position and perform matching. In the accuracy verification experiments of several young people, the average error of each joint position was less than approximately 0.03 m, and the average error of the knee angle was approximately 4.54 to 5.13 degrees. These results indicate that the values estimated by the proposed method are useful as values for evaluating clinical tasks.

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Shift-Adaptive Estimation of Joint Angle Using Instrumented Brace with Two Stretch Sensors Based on Gaussian Mixture Models

Eguchi R., Michael B., Howard M., Takahashi M.

IEEE Robotics and Automation Letters (IEEE Robotics and Automation Letters) 5 ( 4 ) 5881 - 5888 2020.10

© 2016 IEEE. Wearable motion sensing in daily life has attracted attention in various disciplines. Especially, stretchable strain sensors have been instrumented into garments (e.g. brace). To estimate joint motions from such sensors, previous studies have modelled relationships between the sensor strains and motion parameters via supervised/semi-supervised learning. However, typically these only model a single relationship assuming the sensor to be located at a specific point on the body. Consequently, they exhibit reduced performance when the strain-parameter relationship varies due to sensor shifts caused by long-term wearing or donning/doffing of braces. This letter presents a shift-adaptive estimation of knee joint angle. First, a brace is instrumented with two stretch sensors placed at different heights. Next, the different strain-angle relationships at varying brace shift positions are learned using Gaussian mixture models (GMMs). The system then estimates the joint angle from the sensor strains through Gaussian mixture regression using a maximum likelihood shift GMM, which is identified by referring to the two strains in a previous 1 s period. Experimental results indicated that the proposed method estimates the joint angle at multiple shift positions (0-20 mm) with higher accuracy than methods using a single model, single sensor, or referring to the present sensor strains.

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Estimation of body direction based on gait for service robot applications

Yorozu A., Takahashi M.

Robotics and Autonomous Systems (Robotics and Autonomous Systems) 132 2020.10

ISSN 09218890

© 2020 Elsevier B.V. Recently, there have been several studies on the research and development of service robots, such as reception or waiter robots for facilities and companion robots for support of baggage transportation or guidance in public spaces. Several experimental results in real environments have been reported. To realize socially acceptable human–robot interaction for service robots, human recognition, including not only position but also body direction, around the robot is important. Using an RGB-D camera, it is possible to detect the posture of a person. However, because the viewing angle of the camera is narrow, it is difficult to recognize the environment around the robot with a single device. This study proposes the estimation of the body direction based on the gait, that is, not only the position and velocity, but also the state of the legs (stance or swing phase), using laser range sensors installed at shin height. We verify the effectiveness of the proposed method for several patterns of movement, which are seen when a person interacts with the service robot and evaluate measurement accuracy.

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Relationship Between Varus Thrust During Gait and Low Back Pain in Individuals With Knee Osteoarthritis

Iijima H., Suzuki Y., Aoyama T., Takahashi M.

Arthritis Care and Research (Arthritis Care and Research) 72 ( 9 ) 1231 - 1238 2020.09

ISSN 2151464X

Objective: To test the hypothesis that varus thrust visualized during gait is associated with a higher prevalence of low back pain (LBP) in individuals with knee osteoarthritis (OA). Methods: Individuals with knee OA (Kellgren/Lawrence grade ≥1) underwent a gait observation to assess varus thrust. The participants identified LBP and its severity using questionnaires. Logistic regression analyses were performed to examine the association between varus thrust and LBP. Results: We included 205 participants (mean age 68.19 years; 72.20% women). A total of 45 participants (22.0%) showed varus thrust in their painful knee, in whom 31 (68.89%) and 18 (40.00%) were identified as having any LBP and moderate-to-severe LBP (numerical rating scale ≥4 points), respectively. Patients with varus thrust demonstrated a 3.6-fold higher risk of the presence of moderate-to-severe LBP (95% confidence interval [95% CI] 1.62–8.10). In patients with LBP, the presence of varus thrust was associated with more severe LBP intensity (proportional odds ratio 2.25 [95% CI 1.02–4.96]). Conclusion: This study highlights the novel relationship between varus thrust and LBP, which supports the idea of a biomechanical link, the so-called knee–spine syndrome. These findings provide new insight for clarifying the pathogenesis of LBP related to knee OA.

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Human-friendly control system design for two-wheeled service robot with optimal control approach

Sekiguchi S., Yorozu A., Kuno K., Okada M., Watanabe Y., Takahashi M.

Robotics and Autonomous Systems (Robotics and Autonomous Systems) 131 2020.09

ISSN 09218890

© 2020 Elsevier B.V. This paper proposes a novel control system design for a two-wheeled service robot that follows a person as an assistant without knowing the person's destination. For this kind of service robot, the key skill is to realize human-friendly movement. However, appropriate motion always changed depending on the situation. For instance, when the robot is close and person turns toward it, it is important to suppress the robot's acceleration. Likewise, if the person turns away from the robot, the robot should maintain its position within an appropriate area. Therefore, to deal with various required movements, our control system is able to change its properties automatically and suitably depending on the situation by using weights of the cost function in nonlinear model predictive control (NMPC) as a function of the relative distance between the person and the robot. Unlike previous methods, our design includes only one controller. Consequently, we are able to take into account system stability. Moreover, owing to proposing in NMPC framework, it is easy to extend our method by adopting other recognition or goal-setting methods. We conducted simulations using actual human walking data taken by the robot's laser range sensors. The experiments demonstrate that the robot can follow a person who performs U-turn, confirming that our method can produce human-friendly robot movement in a practical scene.

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Gait analysis of patients with distal radius fracture by using a novel laser Timed Up-and-Go system

Fujita K., Iijima H., Eguchi R., Kuroiwa T., Sasaki T., Yokoyama Y., Koyama T., Nimura A., Kato R., Okawa A., Takahashi M.

Gait and Posture (Gait and Posture) 80 223 - 227 2020.07

ISSN 09666362

© 2020 The Authors Background: Postmenopausal women are at risk of fall and fracture with the physical decline. Distal radius fracture (DRF) is considered as the primary fragility fracture, and women with this fracture showed poor results in the usual Timed Up-and-Go (TUG) test, indicating a decline in balance and physical ability. The detailed physical characteristics of female DRF patients have not been extensively examined. Research question: Is the novel laser TUG system able to detect and analyze the detailed gait characteristics in patients with DRF whose physical ability has tended to decline? Methods: In this cross-sectional case control study, the gait characteristics of 32 female patients with DRF who had undergone surgery were evaluated at 2 weeks postoperatively with a laser TUG system to analyze the detailed leg motion during normal TUG test. Forty-three age- and sex-matched non-fractured women were evaluated by the laser TUG system as controls. Lifestyle and present illness were corrected at the time of TUG measurement. Detailed data during laser TUG in both groups were compared statistically, and odds ratio and thread shod of the fracture was elucidated through a logistic regression analysis. Results: DRF patients showed slower speed and had to do more steps to complete the TUG test. Furthermore, asymmetric trajectory and significantly further distance from the marker were observed. Thirteen steps to complete the TUG test was the thread shod of DRF. Significance: Detailed gait characteristics of patients with DRF were detected by the laser TUG system. The gait decline and abnormality could be one of the reasons of consecutive fragility fracture. To prevent secondary fragility fractures, this system can be useful for screening.

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Assessment of motion and muscle activation impacts on low back pain during pregnancy using an inertial measurement unit

Morino S., Yamashita M., Umezaki F., Hatanaka H., Takahashi M.

Applied Sciences (Switzerland) (Applied Sciences (Switzerland)) 10 ( 11 ) 2020.06

© 2020 by the authors. Specific physiological changes during pregnancy exert excessive strain on muscles such as the erector spinae (ES) and contribute to low back pain (LBP). The link between LBP and sit-to-stand (STS) motion has previously been investigated through motion analysis using an inertial measurement unit (IMU); however, the factors leading to LBP have not been revealed. Moreover, clinicians require an effective assessment method for reducing the physical burden on pregnant women. Therefore, the investigation of the relationships between motion, muscle load calculated from musculoskeletal model for pregnancy, and the severity of LBP during STS in pregnant women was conducted. Furthermore, this study proposes a method for assessing motion and muscle load during STS using an IMU. The relationship among (i) motion evaluation indices and ES muscle torque, and (ii) the ES torque and the intensity of LBP during STS was investigated. As the results, significant positive correlations were observed between (i) the angular velocity of the torso in the sagittal plane and ES torque, and (ii) two types of evaluation indices of ES torque and intensity of LBP. The proposed method by an IMU attached to the torso could effectively assess ES load related to LBP during STS in pregnant women.

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State of the Field of waist-mounted sensor algorithm for gait events detection: A scoping review

Iijima H., Takahashi M.

Gait and Posture (Gait and Posture) 79 152 - 161 2020.06

ISSN 09666362

© 2020 Elsevier B.V. Background: A waist-mounted sensor is an attractive option for detecting initial and end of foot contacts during gait in a clinical setting without disturbing the subject's natural gait. Research question: To examine the current state of the field regarding waist-mounted sensor algorithms for gait event detection during locomotion in adults. Methods: A scoping review design was used to search peer-reviewed literature or conference proceedings published through October 2018 for algorithms for gait event detection. We analyzed data from the studies in a descriptive manner. Results: In total, 588 potentially relevant articles were selected, of which 14 (171 participants, mean age: 44.0 years) met the inclusion criteria. We identified 15 algorithms developed using biomechanical theories including the inverted pendulum model that represents gait during level walking. Most algorithms estimated gait events using triaxial acceleration data with an absolute error of approximately 50–100 ms in healthy adults. However, there was a large amount of inter-trial heterogeneity, and only a few algorithms were validated in patients with neurological diseases. Lower gait speed reduced the accuracy of gait event estimation. Significance: There was no algorithm that showed outstanding performance in the estimation of gait events during level walking using the waist-mounted sensor. More comparisons of all available algorithms with an established reference standard for one data-set are needed to identify the best algorithms. As patients with pathological conditions display altered trunk acceleration and slower gait speeds, the development of an algorithm that does not rely on particular signal characteristics and is robust for a wide range of gait speeds is needed before a specific algorithm can be recommended as a valid strategy for clinical practice.

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Estimation of Vertical Ground Reaction Force Using Low-Cost Insole with Force Plate-Free Learning from Single Leg Stance and Walking

Eguchi R., Yorozu A., Fukumoto T., Takahashi M.

IEEE Journal of Biomedical and Health Informatics (IEEE Journal of Biomedical and Health Informatics) 24 ( 5 ) 1276 - 1283 2020.05

ISSN 21682194

© 2013 IEEE. For the evaluation of pathological gait, a machine learning-based estimation of the vertical ground reaction force (vGRF) using a low-cost insole is proposed as an alternative to costly force plates. However, learning a model for estimation still relies on the use of force plates, which is not accessible in small clinics and individuals. Therefore, this paper presents a force plate-free learning from a single leg stance (SLS) and natural walking measured only by the insoles. This method used a linear least squares regression that fits insole measurements during SLS to body weight in order to learn a model to estimate vGRF during walking. Constraints were added to the regression so that vGRF estimates during walking were of proper magnitude, and the constraint bounds were newly defined as a linear function of stance duration. Moreover, a lower bound for the estimated vGRF in mid-stance was added to the constraints to enhance estimation accuracy. The vGRF estimated by the proposed method was compared with force platforms for 4 healthy young adults and 13 elderly adults including patients with mild osteoarthritis, knee pain, and valgus hallux. Through the experiments, the proposed learning method had a normalized root mean squared error under 10% for healthy young and elderly adults with stance durations within a certain range (600-800 ms). From these results, the validity of the proposed learning method was verified for various users requiring assessment in the field of medicine and healthcare.

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Plucking motions for tea harvesting robots using probabilistic movement primitives

Motokura K., Takahashi M., Ewerton M., Peters J.

IEEE Robotics and Automation Letters (IEEE Robotics and Automation Letters) 5 ( 2 ) 3275 - 3282 2020.04

© 2016 IEEE. This letter proposes a harvesting robot capable of plucking tea leaves. In order to harvest high-quality tea, the robot is required to pluck the petiole of the leaf without cutting it using blades. To pluck the leaves, it is necessary to reproduce a complicated human hand motion of pulling while rotating. Furthermore, the rotation and pulling of the hand, and the time taken, vary greatly depending on conditions that include the maturity of the leaves, thickness of the petioles, and thickness and length of the branches. Therefore, it is necessary to determine the amount of translational and rotational movements, and the length of time of the motion, according to each situation. In this study, the complicated motion is reproduced by learning from demonstration. The condition is judged in terms of the stiffness of the branches, which is defined as the force received from the branches per unit length when the gripped leaf is slightly pulled up. Combining the learned motions probabilistically at a ratio determined by the branch stiffness, the appropriate motion is generated, even for situations where no motion is taught. We compared the motions generated by the proposed method with the motions taught by humans, and verified the effectiveness of the proposed method. It was confirmed by experiment that the proposed method can harvest high-quality tea.

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Hip abductor muscle weakness and slowed turning motion in people with knee osteoarthritis

Iijima H., Yorozu A., Suzuki Y., Eguchi R., Aoyama T., Takahashi M.

Journal of Biomechanics (Journal of Biomechanics) 101 2020.03

ISSN 00219290

© 2020 Elsevier Ltd Laser range sensor-based timed up and go (laser-TUG) test can evaluate performance in TUG subtasks (sit-to-walk [STW], walking a short distance, and turning). This study aimed to test the hypothesis that weaker hip abductor muscle strength is more significantly associated with slowed turning speed than with the other TUG subtasks (STW and straight walking) after controlling for quadriceps muscle strength in patients with knee osteoarthritis (OA). Community-dwelling participants with knee OA (Kellgren and Lawrence [K&L] grade ≥ 1; mean age, 68.6 years; 70.3% women) underwent laser-TUG. Spatiotemporal gait parameters in TUG and the TUG subtasks were evaluated as outcome measures. The isometric muscle strength of the hip abductor and quadriceps was measured using a hand-held dynamometer. Multiple linear regression analysis was performed to examine the relationship between muscle strength as an independent variable and spatiotemporal parameters as dependent variables. The relative importance of hip abductor muscle strength was determined using the percentages of unique variance. Participants with weaker hip abductor muscle strength demonstrated 0.094 m/s slower turning speed after adjustment for covariates including quadriceps muscle strength. The unique variance explained by hip abductor muscle strength in turning speed was 2.1%. However, no significant relationships were confirmed between weak hip abductor muscle strength and the time to perform TUG and the straight walking (forward and return) phase. These findings indicate that turning motion may be more sensitive to aggravated hip abductor muscle weakness and may show better response to hip muscle strengthening exercises. Longitudinal studies are warranted to elucidate this issue.

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Head-synced Drone Control for Reducing Virtual Reality Sickness

Watanabe K., Takahashi M.

Journal of Intelligent and Robotic Systems: Theory and Applications (Journal of Intelligent and Robotic Systems: Theory and Applications) 97 ( 3-4 ) 733 - 744 2020.03

ISSN 09210296

© 2019, Springer Nature B.V. Controlling a drone using head-mounted display induces virtual reality (VR) sickness. From previous research, it is known that angular velocity is one of the contributing factors to induce VR sickness, however for drones, linear motion and the interaction between linear and angular motion often occur during operation. In this research, we investigate the effect of each conditions experimentally and proposes a method of controlling a drone to reduce VR sickness. We designed a system that does not make user’s head fixed at one point but allows to move the head freely. At the same time, the head orientation and direction are synced with the drone’s attitude to reduce sensory conflict. Two controllers were compared: joystick control and head control. We tested with a real system and conducted experiments on subjects to verify its effect. The proposed controller reduced angular velocity in the frequency range 0.1 to 10 Hz where a vestibular system becomes most sensitive, and it is demonstrated that reducing sensory conflict contributes to the reduction of VR sickness.

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Contralateral Limb Effect on Gait Asymmetry and Ipsilateral Pain in a Patient with Knee Osteoarthritis: A Proof-of-Concept Case Report

Iijima H., Inoue M., Suzuki Y., Shimoura K., Aoyama T., Madoba K., Takahashi M.

JBJS case connector (JBJS case connector) 10 ( 1 ) 2020.01

CASE: A 77-year-old woman with knee osteoarthritis (OA) complained of right (ipsilateral) knee pain for more than 5 years with gait asymmetry. The OA and quadriceps muscle weakness were more severe in the left (contralateral) knee, but she had no pain. Bracing of the left knee led to decreased gait asymmetry, as determined with an inertial measurement unit, and reduced pain in the right knee. CONCLUSION: This case highlights the contralateral knee effect on ipsilateral chronic knee pain, possibly through gait asymmetry. These findings provide a mechanistic insight into knee OA-related pain in patients with gait asymmetry and suggest a new rehabilitative approach.

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Detailed analysis of the transverse arch of hallux valgus feet with and without pain using weightbearing ultrasound imaging and precise force sensors

Zeidan H., Ryo E., Suzuki Y., Iijima H., Kajiwara Y., Harada K., Nakai K., Shimoura K., Fujimoto K., Takahashi M., Aoyama T.

PLoS ONE (PLoS ONE) 15 ( 1 ) 2020.01

© 2020 Zeidan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background Hallux valgus is the most common forefoot deformity and affects the transverse arch structure and its force loading patterns. This study aims to clarify the differences in the transverse arch structure and the force under the metatarsal heads individually, between normal feet and hallux valgus feet, and between hallux valgus feet with pain and without pain. We further test the association between the parameters of the transverse arch and hallux valgus angle and between the parameters and pain in hallux valgus. Methods Women's feet (105 feet) were divided into normal group (NORM) and hallux valgus group (HVG); and further into subgroups: hallux valgus without pain (HV Pain (-)) and hallux valgus with pain (HV Pain (+)). Transverse arch height and metatarsal heads height were measured using weight-bearing ultrasound imaging. Force under the metatarsal heads was measured using force sensors attached directly on the skin surface of the metatarsal heads. The measurements were taken in three loading positions: sitting, quiet standing and 90% weight shift on the tested foot. Differences between the groups were compared using Student t-test and Wilcoxon Exact test. Multivariate logistic analysis with adjustment for physical characteristics was also conducted. Results Transverse arch height was significantly higher in HVG than in NORM in all positions; there were no significant differences between HV Pain (+) and HV pain (-). Lateral sesamoid wassignificantly higher in HVG and HV Pain (+) than in NORM and HV Pain (-) respectively when bearing 90% of the body weight unilaterally. There was a trend of higher forces under the medial forefoot without significant difference. Transverse arch height and lateral sesamoid height were associated with the hallux valgus angle, while lateral sesamoid height was associated with forefoot pain in hallux valgus deformity. Conclusions This study shows the differences in the transverse arch structure between normal feet and feet with hallux valgus, and between hallux valgus feet with and without pain. This finding is noteworthy when considering future treatments of painful feet, notably the height of the lateral sesamoid which seems to play a role in forefoot pain.

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Velocity measurement improvement of landing radar considering irradiated surface using neural networks

Hidaka M., Takahashi M., Ishida T., Kariya K., Mizuno T., Fukuda S.

Journal of Aerospace Information Systems (Journal of Aerospace Information Systems) 17 ( 5 ) 248 - 256 2020

© 2019 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. In this study, a signal-processing method for the landing radar of a lunar lander is proposed using deep learning. To perform a precise landing, measurement of the relative velocity with respect to the surface is essential. To measure the velocity, the landing radar irradiates the surface with a pulse wave and observes the Doppler shift. High-precision measurement on complex terrains, such as a crater or slope, has always been the problem of landing radar because the irradiated terrain causes a deformation of the reflected pulse wave and strongly affects the measurement accuracy. A system is proposed in this study that performs measurements with high accuracy on complex terrains using convolutional neural networks. In the proposed method, spectrograms are used as input data to consider the effect of irradiated terrain on the measurement data. Experiments show that our method not only improves the measurement accuracy compared with the existing method but also can be implemented from the viewpoint of execution time. Moreover, this paper attempted to deepen the network architecture and input irradiated terrain data simultaneously. It was confirmed that the measurement accuracy was further improved by this enhancement.

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Reducing speed commands in interval management with speed planning

Riedel T., Takahashi M., Itoh E.

Aeronautical Journal (Aeronautical Journal) 189 - 215 2020

ISSN 00019240

© 2019 Royal Aeronautical Society. Flight-deck Interval Management (FIM) is a modern airborne self-spacing technology that improves arrival route throughput and runway utilisation and increases hourly arrival capacity by up to four aircraft per hour and per runway, compared to conventional air traffic controller guided arrivals. The National Aeronautics and Space Administration (NASA) has been the leader in FIM research and formulated a logic that was put to an actual flight test in 2017. Despite the overall success of the project, operational deficiencies concerning the number of speed commands, which led to several recommendations for future research before operational implementation, were discovered. In this study, a new logic that implements a two-stage rule-based selection algorithm was developed to overcome those deficiencies. The proposed logic was compared to NASA's logic on an arrival in Tokyo International Airport with multiple induced error patterns. The results indicate that the new logic significantly decreases the number of speed commands with only minor aggravations in spacing performance. The results that highlight the strengths and weaknesses of both concepts are discussed, and an outlook on and ideas for future research on FIM and the proposed logic are presented.

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Optimal power management considering attitude control and battery deterioration control for spacecraft with vscmg/ipacs

Yoshihara H., Takahashi M.

AIAA Scitech 2020 Forum (AIAA Scitech 2020 Forum) 1 PartF 2020

ISSN 9781624105951

© 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Earth observation satellites repeatedly charge and discharge their batteries in harsh environments, where sunlight illumination and shade occur repetitively; thus, battery power deteriorates rapidly. In this study, variable speed control moment gyro (VSCMG) / integrated power and attitude control system (IPACS), which has both an attitude control function and an energy storage function, was used for a lithium-ion battery and a hybrid. We propose a control law that suppresses the chemical deterioration factor of the battery while achieving attitude control by cooperatively charging and discharging the required power. The proposed method calculates the commands of VSCMG/IPACS and the power distribution ratio of the battery and VSCMG/IPACS at the same time, for power distribution that accounts for the reference torque. The proposed method considers the torque error, the wheel angular velocity variation, and the wheel angular acceleration variation, to ensure attitude control performance. In addition, to suppress the deterioration factor of the battery, an evaluation function considering the SOC and C rate of the battery is designed. While constraints on the output power, motor, and battery are satisfied, we obtain the optimal solution that minimizes the evaluation function. Using the above algorithm, the proposed method can yield optimal power distribution and commands of VSCMG/IPACS.

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Model predictive control of autonomous drone considering model of birds aimed at inducing a flock of birds

Hamabe S., Takahashi M.

AIAA Scitech 2020 Forum (AIAA Scitech 2020 Forum) 1 PartF 2020

ISSN 9781624105951

© 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. In recent years, bird strikes are increasing with the increase in the number of airliner flights. Therefore, measures against bird strikes are required. Collisions between an aircraft and a flock of birds during takeoff and landing are numerous and can cause serious damage. Related works have been conducted to prevent entry of a flock of birds into the runway. The purpose of this study was to guide a flock of birds into avoiding the runway using an autonomous drone. Guidance was successful in simulations and experiments, provided that the drone was located near a flock of birds. Therefore, in this study, assuming that the drones are placed around the runway and far from the flock, we propose a control method to move the drone towards the flock and guide the birds to prevent bird strikes. In order to realize interception and guidance under such conditions, we predict the trajectories of the bird flock using a model of birds. Setting the target position of the drone on the predicted trajectories allows the drone to intercept the birds without unnecessary movement of the drone. Because the drone is in the same speed range as the birds, we determine the drone’s control input so as to satisfy the velocity constraint using model predictive control (MPC). In this study, we propose a control method for autonomous drones that considers the model of birds, aimed at guiding a flock of birds to prevent bird strike. We verify the performance of the proposed method by conducting numerical analysis based on a model of a realistic runway.

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A Multimodal Path Planning Approach to Human Robot Interaction Based on Integrating Action Modeling

Kawasaki Y., Yorozu A., Takahashi M., Pagello E.

Journal of Intelligent and Robotic Systems: Theory and Applications (Journal of Intelligent and Robotic Systems: Theory and Applications) 100 ( 3-4 ) 955 - 972 2020

ISSN 09210296

© 2020, Springer Nature B.V. To complete a task consisting of a series of actions that involve human-robot interaction, it is necessary to plan a motion that considers each action individually as well as in relation to the following action. We then focus on the specific action of “approaching a group of people” in order to accurately obtain human data that is used to make the performance of tasks involving interactions with multiple people more smooth. The movement depends on the characteristics of the important sensors used for the task and on the placement of people at and around the destination. Considering the multiple tasks and placement of people, the pre-calculation of the destinations and paths is difficult. This paper thus presents a system of navigation that can accurately obtain human data based on sensor characteristics, task content, and real-time sensor data for processes involving human-robot interaction (HRI); this method does not navigate specifically toward a previously determined static point. Our goal was achieved by using a multimodal path planning based on integration of action modeling by considering both voice and image sensing of interacting people as well as obstacle avoidance. We experimentally verified our method by using a robot in a coffee shop environment.

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Terrain relative navigation enhanced with sar for moon’s shadowed regions

Hidaka M., Takahashi M., Ishida T., Fukuda S.

AIAA Scitech 2020 Forum (AIAA Scitech 2020 Forum) 1 PartF 2020

ISSN 9781624105951

This study proposes a terrain relative navigation (TRN) method to estimate spacecraft positions in the shadowed regions of the moon with high precision by combining the camera image and the synthetic aperture radar (SAR) data. TRN, which estimates the position of a spacecraft by comparing the preliminary terrain information stored in a database with the observed terrain, is an effective method of correcting the drift errors of inertial measurement units (IMUs). Optical cameras are primarily used for TRN sensors to observe the terrain; however, shadow images do not have enough characteristic points to match with the database. SAR is a form of radar that can generate high-resolution photo-like images, regardless of light conditions. In this study, we propose the use of SAR as navigation sensors and demonstrate effectiveness of SAR.

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Pilot-centered evaluation of flight-deck interval management control laws using an a320 simulator

Riedel T., Takahashi M., Itoh E., Frost P., Feuerle T.

Journal of Aircraft (Journal of Aircraft) 57 ( 5 ) 974 - 984 2020

ISSN 00218669

Recent research on flight-deck interval management technology, including the findings of a flight-test demonstration conducted by NASA, led to the development of an alternative control logic for flight-deck interval management, termed as “interval management–speed planning.” As this logic demonstrated promising results in numerical simulations, for the first time, test pilots and airline pilots were invited to evaluate the system in an Airbus A320 simulator, using an avionics setup similar to the one employed in NASA’s flight test, on an approach for the Tokyo International Airport. A qualitative and quantitative survey was conducted in which the pilots’ opinions pertaining to their acceptance of the interval management operation and comprehension of the system behavior using both the original and alternative control logic, as well as a modified graphical user interface, were sought. The results indicated that the new control logic was well accepted by the pilots, confirming some of the results and hypotheses from the numerical simulation; nevertheless, it was indicated that further research on the user interface is needed to make full use of the logic’s capability.

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Optimisation of interval management - Speed planning using SMPSO

Riedel T., Takahashi M., Itoh E.

Aeronautical Journal (Aeronautical Journal) 124 ( 1281 ) 1819 - 1845 2020

ISSN 00019240

Recent research on Flight-deck Interval Management (FIM), a modern technology for increasing safety and improving airspace and runway utilisation through self-spacing, has led to the development of a new rule-based logic for FIM, namely Interval Management - Speed Planning (IM-SP). In an initial benchmark study, IM-SP showed good spacing performance with a significant reduction in speed commands, a major area of concern with previous FIM logics, resulting in a lower burden on the flight crew during FIM operation. Nevertheless, there remains scope for improvement in other aspects, such as fuel burn. In this study, the internal cost function of IM-SP is further analysed and optimised using speed-constrained multi-objective particle swarm optimisation to improve the performance of IM-SP under the multiple objectives of FIM. The optimisation renders new settings that address the problem areas, improve the speed commands and enhance the overall quality of IM-SP. Two distinctive solutions, viz. a spacing performance optimised setting and a fuel burn optimised setting, are further analysed and discussed, and directions for follow-up research are explored.

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Reinforcement Learning of Trajectory Distributions: Applications in Assisted Teleoperation and Motion Planning

Ewerton M., Maeda G., Koert D., Kolev Z., Takahashi M., Peters J.

IEEE International Conference on Intelligent Robots and Systems (IEEE International Conference on Intelligent Robots and Systems) 4294 - 4300 2019.11

ISSN 9781728140049

© 2019 IEEE. The majority of learning from demonstration approaches do not address suboptimal demonstrations or cases when drastic changes in the environment occur after the demonstrations were made. For example, in real teleoperation tasks, the demonstrations provided by the user are often suboptimal due to interface and hardware limitations. In tasks involving co-manipulation and manipulation planning, the environment often changes due to unexpected obstacles rendering previous demonstrations invalid. This paper presents a reinforcement learning algorithm that exploits the use of relevance functions to tackle such problems. This paper introduces the Pearson correlation as a measure of the relevance of policy parameters in regards to each of the components of the cost function to be optimized. The method is demonstrated in a static environment where the quality of the teleoperation is compromised by the visual interface (operating a robot in a three-dimensional task by using a simple 2D monitor). Afterward, we tested the method on a dynamic environment using a real 7-DoF robot arm where distributions are computed online via Gaussian Process regression.

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Learning Trajectory Distributions for Assisted Teleoperation and Path Planning

Ewerton M., Arenz O., Maeda G., Koert D., Kolev Z., Takahashi M., Peters J.

Frontiers in Robotics and AI (Frontiers in Robotics and AI) 6 2019.09

Several approaches have been proposed to assist humans in co-manipulation and teleoperation tasks given demonstrated trajectories. However, these approaches are not applicable when the demonstrations are suboptimal or when the generalization capabilities of the learned models cannot cope with the changes in the environment. Nevertheless, in real co-manipulation and teleoperation tasks, the original demonstrations will often be suboptimal and a learning system must be able to cope with new situations. This paper presents a reinforcement learning algorithm that can be applied to such problems. The proposed algorithm is initialized with a probability distribution of demonstrated trajectories and is based on the concept of relevance functions. We show in this paper how the relevance of trajectory parameters to optimization objectives is connected with the concept of Pearson correlation. First, we demonstrate the efficacy of our algorithm by addressing the assisted teleoperation of an object in a static virtual environment. Afterward, we extend this algorithm to deal with dynamic environments by utilizing Gaussian Process regression. The full framework is applied to make a point particle and a 7-DoF robot arm autonomously adapt their movements to changes in the environment as well as to assist the teleoperation of a 7-DoF robot arm in a dynamic environment.

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Stair climbing ability in patients with early knee osteoarthritis: Defining the clinical hallmarks of early disease

Iijima H., Eguchi R., Shimoura K., Aoyama T., Takahashi M.

Gait and Posture (Gait and Posture) 72 148 - 153 2019.07

ISSN 09666362

© 2019 Elsevier B.V. Background: A growing clinical interest has been shown towards identifying knee osteoarthritis (OA) patients at earlier stages. The early detection of knee OA may allow for more effective interventions. Research question: The aim of this study was to determine the discriminative ability of a stair-climb test (SCT) in identifying patients with early knee OA, and to determine if descending stair time during the SCT is better than ascending stair time for the identification of these patients. Methods: This study was a secondary, cross-sectional analysis of baseline data from a randomized controlled trial. Adults with moderate to severe knee pain were enrolled (n = 57; mean age 58.9 years; 71.9% women). Each participant performed an 11-step SCT (11-SCT) while wearing shoes with a pressure sensor insole. A receiver operating characteristic analysis was used to examine the discriminative power of 11-SCT for identifying early knee OA (Kellgren and Lawrence grade 1). The discriminative power was also compared between the ascending and descending 11-SCT time as evaluated by the pressure sensor. Results: The 11-SCT time in patients with early knee OA was 0.55 s longer than that in those with symptomatic non-radiographic OA. A one-second increase in the 11-SCT time was significantly associated with 1.9-fold increased odds of early knee OA being present. The 11-SCT value with the best balance of sensitivity and specificity for identifying early knee OA was 8.33 s (area under the curve: 0.711). The descending time was not significantly better than the ascending time for identifying early knee OA. Significance: This study determined the time values of an 11-SCT that may be useful for identifying early knee OA patients. These preliminary findings may serve as the foundation for future studies investigating the clinical hallmarks associated with early knee OA.

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Effects of interaction between varus thrust and ambulatory physical activity on knee pain in individuals with knee osteoarthritis: an exploratory study with 12-month follow-up

Iijima H., Aoyama T., Eguchi R., Takahashi M., Matsuda S.

Clinical Rheumatology (Clinical Rheumatology) 38 ( 6 ) 1721 - 1729 2019.06

ISSN 07703198

© 2019, International League of Associations for Rheumatology (ILAR). Introduction: This study aimed to examine the interaction effect between ambulatory physical activity (PA) and varus thrust on knee pain in individuals with knee osteoarthritis (OA). Method: Subjects (n = 207; mean age: 73.1 years, 71.5% women) in orthopedic clinics with diagnosed knee OA (Kellgren/Lawrence grade ≥ 1) were enrolled in this 12-month observational cohort study. Participants underwent gait observation for varus thrust assessment and pedometer-based ambulatory PA measurements at baseline and 12-month follow-up. Knee pain intensity was assessed using the Japanese Knee Osteoarthritis Measure pain subscale as a primary outcome measure. Multiple linear regression analyses were performed to evaluate ambulatory PA–thrust interaction on knee pain intensity. Results: Ninety-two subjects (mean age, 73.4 years; 68.5% women) completed the 12-month follow-up assessment. Baseline ambulatory PA–thrust interaction was significant (P = 0.017) in the cross-sectional analysis, adjusting for covariates, which yielded R2 = 0.310. Subgroup analysis showed that varus thrust was significantly associated with worse knee pain in subjects walking ≥ 5000 steps/day adjusting for covariates (beta: 7.94; 95% CI: 3.82, 12.1; P < 0.001) with a higher predictive ability (R2 = 0.664). In contrast, ambulatory PA–thrust interaction in the longitudinal analysis showed no significant association with knee pain changes. Conclusions: Ambulatory PA interacted with varus thrust in the association with knee pain, as coexisting high ambulatory PA and varus thrust had the strongest association with higher knee pain. Maximal pain relief effects might be achieved when both ambulatory PA and varus thrust are treated simultaneously, rather than treating each separately.

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Design of Vibration-Isolating Bed for Ambulances Using Inerter

Koyanagi R., Takahashi M.

2019 12th Asian Control Conference, ASCC 2019 (2019 12th Asian Control Conference, ASCC 2019) 567 - 572 2019.06

ISSN 9784888983006

© 2019 JSME. A vibration-isolating bed for ambulances using an inerter is proposed. The structure of the bed is assumed to consist of a bottom frame fixed to the ambulance floor and an upper frame on which the stretcher is placed. Both are connected only by the suspension, including the inerter, in the vertical and horizontal directions. Because the inerter can reduce the gain of the high frequency band and delay the response, the time when maximum acceleration is applied to bed can be shortened by passively in a limited space in ambulance. We consider the bed as a plant and the suspension as a controller, and then formulate the state equation. To reduce the acceleration within the movable range of the bed, the controller that minimizes the H∞ norm of the transfer function from the external force acting on the bed to acceleration is calculated by bilinear matrix inequality. The transfer function determines the structure and coefficient of the suspension. The usefulness of the bed is verified by numerical simulations.

Walking Measurement System Including Turning Motion Assessment Using Depth Sensors

Ono T., Takahashi M.

2019 12th Asian Control Conference, ASCC 2019 (2019 12th Asian Control Conference, ASCC 2019) 861 - 866 2019.06

ISSN 9784888983006

© 2019 JSME. Recently, with the aging of the population, fall accidents of elderly people are increasing. In order to reduce fall accidents, it is necessary to detect the walking ability decline of elderly people. People with medical knowledge, such as physiotherapists, qualitatively evaluate and judge walking ability from experiences and tendencies by a walking test. However, in this case, it is difficult to examine many subjects and to evaluate them quantitatively. Therefore, it is increasing to the demand for walking measurement systems using instruments. Requirement of this system is not that it can be measured with high accuracy but that it is simple, inexpensive and accurate enough for gait ability evaluation. Therefore, three-dimensional motion analysis device that are high accuracy but expensive and need to be equipped with markers are not suitable.

Satellite Attitude Control and Power Tracking with VSCMGs during Large-angle and Agile Attitude Maneuvers

Yoshihara H., Takahashi M.

2019 12th Asian Control Conference, ASCC 2019 (2019 12th Asian Control Conference, ASCC 2019) 1613 - 1618 2019.06

ISSN 9784888983006

© 2019 JSME. In recent years, the use of VSCMG/IPACS for satellites has been considered, because Earth observation satellites are required to have agility and miniaturization. However, in previous research, the control laws of VSCMG/IPACS at large-angle and agile attitude maneuvers have not been studied. In this study, we clarify that it is impossible for conventional methods to achieve large-angle and agile attitude maneuvers, while accurately tracking power. Therefore, we propose a system capable of simultaneous satellite attitude control and power tracking with VSCMG during large-angle and agile attitude maneuvers. The proposed steering law switches the steering laws according to singularities, and enables the satellite to change attitude quickly without power errors. In addition, numerical simulations demonstrate through comparison that the proposed steering law is more useful than conventional steering laws.

Insole-Based Estimation of Vertical Ground Reaction Force Using One-Step Learning with Probabilistic Regression and Data Augmentation

Eguchi R., Takahashi M.

IEEE Transactions on Neural Systems and Rehabilitation Engineering (IEEE Transactions on Neural Systems and Rehabilitation Engineering) 27 ( 6 ) 1217 - 1225 2019.06

ISSN 15344320

© 2001-2011 IEEE. An insole-based estimation of the vertical ground reaction force (vGRF) is proposed as an alternative to costly force plates for the evaluation of pathological gait. However, machine learning techniques for estimation still rely on the use of force plates. Moreover, measuring plural walking steps in order to prevent overfitting induces fall risks and physically taxes the patients. Therefore, this paper presents an accessible and efficient learning scheme for the insole-based estimation of vGRF. In this system, we employ a low-cost scale as an alternative to force plates. Then, we use Gaussian process regression (GPR) to learn a model in order to estimate vGRF without overfitting of small-sized data sets corrupted by measurement errors and noise of the devices. In addition, we propose a 'one-step learning' scheme based on a probabilistic data augmentation. This approach augments actual measurements of a minimum (just one) walking step to a virtual data set for plural steps by considering their typical variability between steps. In experiments, the GPR models learned from two walking steps estimated vGRF with mean errors of 8% or under for entire/local magnitudes. Moreover, the learning from one step with probabilistic augmentation enhanced the estimation accuracy.

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Spatiotemporal and kinetic gait analysis system based on multisensor fusion of laser range sensor and instrumented insoles

Eguchi R., Yorozu A., Takahashi M.

Proceedings - IEEE International Conference on Robotics and Automation (Proceedings - IEEE International Conference on Robotics and Automation) 2019-May 4876 - 4881 2019.05

ISSN 9781538660263

© 2019 IEEE. Tracking of human legs during walking are key technologies for gait analysis evaluating the movement function of the elderly and patients with gait disorders. Although the motion capture cameras are the gold standard method for gait analysis because of their high accuracy, they are not always accessible in clinical sites because of their cost, scale, and usability. In response, a laser range sensor (LRS), which is used for obstacle avoidance and human detection of mobile robots, has recently been employed for tracking of leg motions. Some previous studies set LRS at shin height and tracked leg motions during walking using three or five observation patterns and the Kalman filtering and data association methods. However, these systems had difficulty in tracking during walking along a circular trajectory including frequent overlaps and occlusions of legs. Therefore, this paper presents a spatiotemporal and kinetic gait analysis system using a single LRS and instrumented insoles and proposes a multisensor fusion algorithm for tracking leg motions. The instrumented insoles are in-shoe devices embedded force sensors and can detect accurate timings of gait events via force sensing. The system identifies gait phases by the fusion algorithm and switches acceleration input added to motion models of tracked legs for the Kalman filter and data association. The tracking performance of the proposed system was evaluated by measuring walking on a circular trajectory in experiments.

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Proximal gait adaptations in individuals with knee osteoarthritis: A systematic review and meta-analysis

Iijima H., Shimoura K., Ono T., Aoyama T., Takahashi M.

Journal of Biomechanics (Journal of Biomechanics) 87 127 - 141 2019.04

ISSN 00219290

© 2019 Elsevier Ltd Clarifying proximal gait adaptations as a strategy to reduce knee joint loading and pain for individuals with knee osteoarthritis (OA) contributes to understanding the pathogenesis of multi-articular OA changes and musculoskeletal pain in other joints. We aimed to determine whether biomechanical alterations in knee OA patients during level walking is increased upper trunk lean in the frontal and sagittal planes, and subsequent alteration in external hip adduction moment (EHAM) and external hip flexion moment (EHFM). A literature search was conducted in PubMed, PEDro, CINAHL, and Cochrane CENTRAL through May 2018. Where possible, data were combined into a meta-analysis; pooled standardized mean differences (SMD) of between knee OA patients and healthy adults were calculated using a random-effect model. In total, 32 articles (2037 participants, mean age, 63.0 years) met inclusion criteria. Individuals with knee OA had significantly increased lateral trunk lean toward the ipsilateral limb (pooled SMD: 1.18; 95% CI: 0.59, 1.77) along with significantly decreased EHAM. These subjects also displayed a non-significantly increased trunk/pelvic flexion angle and EHFM. The GRADE approach judged all measures as “very low.” These results may indicate that biomechanical alterations accompanying knee OA are associated with increased lateral trunk lean and ensuing alterations in EHAM. Biomechanical alterations in the sagittal plane were not evident. Biomechanical adaptations might have negative sequelae, such as secondary hip abductor muscle weakness and low back pain. Thus, investigations of negative sequelae due to proximal gait adaptations are warranted.

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Concurrent validity and measurement error of stair climb test in people with pre-radiographic to mild knee osteoarthritis

Iijima H., Shimoura K., Eguchi R., Aoyama T., Takahashi M.

Gait and Posture (Gait and Posture) 68 335 - 339 2019.02

ISSN 09666362

© 2018 Elsevier B.V. Background: Stair climbing is the task first affected in patients with knee osteoarthritis (OA); therefore, the precise measurement of time required to climb stairs is important to identify mobility limitations, particularly in the early phase of knee OA. Research question: This study aimed to examine the test-retest reliability, measurement error, and concurrent validity of the stopwatch-based stair-climb test (SCT) in adults with pre-radiographic to mild knee OA. Methods: Fifty-nine participants (mean age, 59.1 [range, 50–69] years; 72.9% female) with Kellgren and Lawrence grade ≤2 disease underwent an 11-step SCT (11-SCT) in accordance with the Osteoarthritis Research Society International recommended method while wearing pressure sensor-mounted standard shoes that is used as a gold standard procedure. Test-retest reliability, measurement errors, and the concurrent validity of the stopwatch-based 11-SCT were evaluated. Results: The test-retest reliability of the stopwatch-based 11-SCT was excellent (intra-class correlation coefficient 1,1 [ICC 1,1 ], 0.952; 95% confidence interval [CI], 0.560 to 0.985; p < 0.001) and the minimal detectable change 95 was 0.102 s. Concurrent validity was excellent (ICC 2,1 : 0.957; 95% CI: 0.661 to 0.986; p < 0.001). Significance: The stopwatch-based 11-SCT had high test-retest reliability and high concurrent validity, which justify its clinical use for identifying mobility limitations in individuals with pre-radiographic to mild knee OA. A difference of 0.2 s in the stopwatch-based 11-SCT time would be considered a true difference beyond a 95% measurement error.

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Trunk movement asymmetry associated with pain, disability, and quadriceps strength asymmetry in individuals with knee osteoarthritis: a cross-sectional study

Iijima H., Eguchi R., Aoyama T., Takahashi M.

Osteoarthritis and Cartilage (Osteoarthritis and Cartilage) 27 ( 2 ) 248 - 256 2019.02

ISSN 10634584

© 2018 Osteoarthritis Research Society International Objective: This study examined 1) the clinical relevance of trunk movement asymmetry, which was evaluated using a trunk-mounted inertial measurement unit (IMU), and 2) the relationship between trunk movement asymmetry and lower limb muscle strength asymmetry in individuals with knee osteoarthritis (OA). Design: One-hundred-thirty-one participants (mean age, 74.2 years; 71.8% female; Kellgren and Lawrence [K&L] grade ≥1) underwent gait analysis at their preferred pace for IMU-based measurement of trunk movement asymmetry (harmonic ratio [HR] and improved HR). The isometric strength of quadriceps and hip abductors was evaluated using a hand-held dynamometer. Pain and disability level were evaluated using a validated self-reported questionnaire. Multiple regression analyses with covariate adjustment were performed to examine the relationship between trunk movement asymmetry (independent variable) and pain, disability level, or muscle strength asymmetry (dependent variables). Results: Individuals with severe knee OA (K&L grade ≥3) had increased trunk movement asymmetry in the medio-lateral axis compared to those with a K&L grade of 1. Increased trunk movement asymmetry was associated with a greater knee pain and disability. The increased trunk movement asymmetry was significantly associated with an increase in the asymmetry of quadriceps strength, but not with asymmetry in the strength of hip abductor. Conclusion: Our findings indicate that increased medio-lateral trunk movement asymmetry may be an indicator of impairment, rather than adaptation, in individuals with knee OA. This preliminary finding warrants validation by future study. Paying close attention to medio-lateral trunk movement asymmetry may be key to our understanding of OA-related pain and disability.

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Evaluating applied flight-deck interval management using monte carlo simulations on the k-supercomputer

Riedel T., Takahashi M., Tatsukawa T., Itoh E.

Transactions of the Japan Society for Aeronautical and Space Sciences (Transactions of the Japan Society for Aeronautical and Space Sciences) 62 ( 6 ) 299 - 309 2019

ISSN 05493811

© 2019 The Japan Society for Aeronautical and Space Sciences. Increasing air traffic and airport congestion calls for solutions to improve traffic throughput. In this paper, we evaluate one solution, Flight-deck Interval Management and its underlying logic, particularly in terms of its utility. An environment to simulate traffic engaged in interval management on the most common arrival routes toward Tokyo International Airport was set up and run as a large-scale Monte Carlo simulation on the K-Supercomputer. The results show that under low wind conditions in particular, spacing goal times with a standard deviation of less than 5 s can be achieved and a speed tolerance mode can reduce the number of speed commands without compromising performance.

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Signal processing of landing radar considering irradiated surface characteristics using convolutional neural networks

Hidaka M., Takahashi M., Ishida T., Kariya K., Mizuno T., Fukuda S.

AIAA Scitech 2019 Forum (AIAA Scitech 2019 Forum) 2019

ISSN 9781624105784

© 2019, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. In this paper, a signal-processing method for a lunar lander using deep learning is proposed. The ability for pinpoint soft landing on a lunar/planetary surface broadens the range of scientific and exploration missions. To perform pinpoint landing, measurement of the relative velocity with respect to the surface is essential. Landing radar is a sensor that measures the relative velocity. To measure the velocity, the landing radar irradiates the surface with a pulse wave and observes the Doppler shift. High-precision measurement on complex terrains, a crater, or a slope has always been the problem of landing radar because the irradiated terrains strongly affect the accuracy. We propose a measurement system that performs with high accuracy on complex terrains using convolutional neural networks. Moreover, we confirm that the proposed method could improve the measurement accuracy compared with the existing method.

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Service robot using estimation of body direction based on gait for human-robot interaction

Yorozu A., Takahashi M.

Advances in Intelligent Systems and Computing (Advances in Intelligent Systems and Computing) 867 199 - 209 2019

ISSN 9783030013691

© 2019, Springer Nature Switzerland AG. Recently, there have been several studies on the research and development of service robots, and experimental results in real environments have been reported. To realize socially acceptable human-robot interaction for service robots, human recognition, including not only position but also body direction, around the robot is important. Using an RGB-D camera, it is possible to detect the posture of a person. However, because the viewing angle of the camera is narrow, it is difficult to recognize the environment around the robot with a single device. This study proposes the estimation of the body direction based on the gait, that is, not only the position and velocity, but also the state of the legs (stance or swing phase), using laser range sensors installed at shin height. We verify the effectiveness of the proposed method for several patterns of movement, which are seen when a person interacts with the service robot.

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Optimal Trajectory Planning of Aircraft for Fair-Sharing of Noise

Saito Y., Yoshimura S., Inoue M., Takahashi M., Sugihara Y.

IFAC-PapersOnLine (IFAC-PapersOnLine) 52 ( 8 ) 368 - 374 2019

© 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. In this paper, we propose a trajectory planning of aircraft to ensure the reduction and fair-sharing of aircraft noise. The fair-sharing of noise is realized by dispersing aircraft trajectories. The proposed trajectory planning consists of two stages. In the first stage, a performance index, which evaluates the accumulated noise for all areas, is calculated. The index, which takes into account noise accumulation, plays an essential role for trajectory dispersion. In the second stage, using the index, an optimization problem of planning aircraft trajectories is solved. Repeating these stages in a day, we realize to reduce and spatially share the noise. The effectiveness of the method is verified in a numerical experiment with actual flight data.

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Nonlinear model predictive control for two-wheeled service robots

Sekiguchi S., Yorozu A., Kuno K., Okada M., Watanabe Y., Takahashi M.

Advances in Intelligent Systems and Computing (Advances in Intelligent Systems and Computing) 867 452 - 463 2019

ISSN 9783030013691

© 2019, Springer Nature Switzerland AG. Two-wheeled service robots capable of following a person are an active research topic. These robots will support and follow customers like tourists to many places. It is necessary that an appropriate distance be maintained between the human and the robot. In addition, robots need to not only approach but also turn toward the human to provide services when the human stops walking. Therefore, the control system should change its property depending on the situation. However, many of the previous researches report an algorithm having only one property. Thus, this research proposed a motion control system of a two-wheeled service robot that could turn around while simultaneously following a human. To achieve this, we use nonlinear model predictive control (NMPC) and evaluation function weights depending on the relative distance between robots and human.

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Multimodal path planning using potential field for human–robot interaction

Kawasaki Y., Yorozu A., Takahashi M.

Advances in Intelligent Systems and Computing (Advances in Intelligent Systems and Computing) 867 597 - 609 2019

ISSN 9783030013691

© 2019, Springer Nature Switzerland AG. In a human–robot interaction, a robot must move to a position where the robot can obtain precise information of people, such as positions, postures, and voice. This is because the accuracy of human recognition depends on the positional relation between the person and robot. In addition, the robot should choose what sensor data needs to be focused on during the task that involves the interaction. Therefore, we should change a path approaching the people to improve human recognition accuracy for ease of performing the task. Accordingly, we need to design a path-planning method considering sensor characteristics, human recognition accuracy, and the task contents simultaneously. Although some previous studies proposed path-planning methods considering sensor characteristics, they did not consider the task and the human recognition accuracy, which was important for practical application. Consequently, we present a path-planning method considering the multimodal information which fusion the task contents and the human recognition accuracy simultaneously.

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Minimum-time attitude maneuver and robust attitude control of small satellite mounted with data relay communication antenna

Mori K., Takahashi M.

Applied Sciences (Switzerland) (Applied Sciences (Switzerland)) 9 ( 5 ) 2019

© 2019 by the authors. This paper proposes a nonlinear control method for carrying out Minimum-time satellite attitude maneuver and antenna motion which have robustness against model uncertainty. In recent years, small Earth observation satellites have been utilized and expected to maneuver rapidly in missions such as multi-target acquisition. On the other hand, small satellites need to send the observation data to ground station. Recently, small Earth observation satellites acquire high-resolution data, resulting in an increase in the time required for data communication. Thus, small satellites need to use inter-orbit communication link through Data Relay test satellite sending data from Data Relay communication (DRC) antenna. In conventional operations, the antenna motion is implemented after satellite attitude maneuver. However, this method has a time delay between the completion of the attitude maneuver and the start of data communication. The purpose of this study is to extend the time of earth observation and data communication by carrying out satellite maneuver and antenna motion concurrently. Because small satellite mounted with DRC antenna has large mass ratio of the antenna, we cannot ignore time variability of the moment of inertia of the whole system and reaction torque generated by antenna motion. Hence, in order to take the influence of the antenna motion into consideration, we combine a satellite attitude control system and an antenna drive system into one control system by governing equations and constructing the optimal control problem. We convert the optimal control problem into a NLP by discretizing the control input (a series of pulses) to minimize the final time of the total maneuver that includes the antenna adjustment. In addition, it is considered that a model uncertainty and unknown disturbance occurs in real space. Thus, we have to design feedback controller to secure robustness in model error and unknown disturbance. Accordingly in order to propose a nonlinear control method for carrying out minimum-time satellite attitude maneuver and antenna motion which have robustness against model uncertainty and unknown disturbance, we calculate a reference attitude by application of optimal control input torque to ideal satellite model and design servo controller by using state-dependent Riccati equation (SDRE) control method in order to track time-variant reference attitude.

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Minimum-time attitude maneuver and robust attitude control of small satellite mounted with communication antenna

Mori K., Takahashi M.

AIAA Scitech 2019 Forum (AIAA Scitech 2019 Forum) 2019

ISSN 9781624105784

© 2019 by Xin Ning. Published by the American Institute of Aeronautics and Astronautics, Inc. This paper proposes a simultaneous control method for small satellites mounted with a communication antenna; the objective is to reduce the time involved in satellite maneuver and antenna motion. Recently, small Earth observation satellites have been utilized, even though agile large angle satellite attitude maneuver has been in demand. Small Earth observation satellites acquire high-resolution data, resulting in an increase in the time required for data communication. Therefore, it has become important to ensure that small Earth observation satellites are capable of being maneuvered rapidly so that communication time can be extended by using a data relay system. The purpose of this study is to extend the time for Earth observation and data communication even if satellite has model uncertainty or space disturbance. In order to achieve this, we propose a simultaneous control method for satellite maneuver and antenna motion by using a nonlinear programming problem (NLP) and robust servo control method by using the state dependent Riccati equation (SDRE).

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Milp-based dual-arm motion planning considering shared transfer path for pick-up and place

Kurosu J., Yorozu A., Takahashi M.

Advances in Intelligent Systems and Computing (Advances in Intelligent Systems and Computing) 867 67 - 77 2019

ISSN 9783030013691

© 2019, Springer Nature Switzerland AG. One of the most basic tasks that a dual-arm robot does is pick-up and place work. Pick-up and place work consists of tasks in which the robot carries objects from a start position (initial position) to a goal position. The following three important points should also be considered when the dual-arm robot does this work efficiently: (1) collision avoidance of the arms, (2) which arm should move an object, and (3) the order in which the objects should be picked up and placed. In addition, dual-arm robot has operation range constraints. Depending on the position relationship between a start position and goal position, unless both arms are used, the object may not be transferred to a goal position. In this paper, we define the transfer path which must use both arms as “shared transfer path”. First, we use mixed integer linear programming (MILP) based planning for the pick-up and place work to determine which arm should move an object and in which order these objects should be moved while considering the dual-arm robot’s operation range. Second, we plan the path using the rapidly exploring random tree (RRT) so that the arms do not collide, enabling the robot to perform efficient pick-up and place work based on the MILP planning solution. The effectiveness of proposed method is confirmed by simulations and experiments using the HIRO dual-arm robot.

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Autonomous Navigation Using Multimodal Potential Field to Initiate Interaction with Multiple People

Kawasaki Y., Yorozu A., Takahashi M.

IEEE International Conference on Intelligent Robots and Systems (IEEE International Conference on Intelligent Robots and Systems) 7654 - 7659 2018.12

ISSN 9781538680940

© 2018 IEEE. In a human-robot interaction, a robot needs to move to a position where the robot can obtain high reliability data of people, such as positions, postures, and voice. This is because the human recognition reliability depends on the positional relation between the people and the robot. In addition, the robot should choose the sensor data which is necessary to perform the interaction task. Therefore, it is necessary to navigate the robot to the position to obtain the data for initiation of the interaction task. Accordingly, we need to design a path-planning method considering sensor characteristics, human recognition reliability, and task contents. Although previous studies proposed path-planning methods using an interaction potential considering sensor characteristics, they did not consider the task contents and the human recognition reliability, which are important for practical application and did not applied to interaction with multiple people. Consequently, we present a path-planning method considering the task contents and the human recognition reliability using multimodal potential field integrating these information. We verified effectiveness of the path-planning method for interaction with multiple people.

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Accessible Calibration of Insole Force Sensors Using the Wii Balance Board for Kinetic Gait Analysis

Eguchi R., Takahashi M.

Proceedings of IEEE Sensors (Proceedings of IEEE Sensors) 2018-October 2018.12

ISSN 9781538647073

© 2018 IEEE. This paper presents a novel calibration method of insole sensors to estimate vertical ground reaction force (vGRF) during walking using the Wii Balance Board (WBB) as an accessible alternative to costly force plates. The sensor forces were weighted using linear least-squares regression to fit to the measurements of the WBB during walking and standing. By comparison with force plates, the accuracies of the vGRF estimated by the method with walking through the WBB were equivalent to the force plate-based calibration. In addition, the method using standing on the WBB did not have large deteriorations when compared to the above methods.

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Interaction between low back pain and knee pain contributes to disability level in individuals with knee osteoarthritis: a cross-sectional study

Iijima H., Suzuki Y., Aoyama T., Takahashi M.

Osteoarthritis and Cartilage (Osteoarthritis and Cartilage) 26 ( 10 ) 1319 - 1325 2018.10

ISSN 10634584

© 2018 Osteoarthritis Research Society International Objective: To test the hypothesis that the interaction between low back pain (LBP) and knee pain intensity contributes to the disability level of individuals with knee osteoarthritis (OA). Design: Community-dwelling participants with knee OA (Kellgren/Lawrence [K/L] grade ≥1) were enrolled. LBP and its severity were identified using questionnaires. Knee pain severity and disability level were evaluated using the Japanese Knee Osteoarthritis Measure (JKOM) subscale. Multiple linear regression analyses were performed to examine the effect of the LBP–knee pain interaction, an independent variable, on disability, a dependent variable. Results: A total of 260 participants (age, 48–88 years; 77.7% women) were included. Of them, 151 (58.1%) had LBP. The LBP–knee pain interaction was significantly associated with disability after the adjustment for covariates. A post-hoc subgroup analysis revealed that the relationship between knee pain intensity and disability level was higher in individuals with LBP (beta: 0.621 points; 95% confidence interval [CI]: 0.511 to 0.731 points) than in those without LBP (beta: 0.402 points; 95% CI: 0.316 to 0.487 points). Conclusions: LBP interacts with knee pain intensity and contributes to disability level in individuals with knee OA. Coexisting LBP and knee pain had a stronger impact on disability level than LBP or knee pain alone. These findings highlight the potential deteriorative effects of the LBP–knee interaction on disability. Maximal treatment effects for disability might be achieved when LBP and knee pain are targeted simultaneously, rather than separately.

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Gait analysis of pregnant patients with lumbopelvic pain using inertial sensor

Tanigawa A., Morino S., Aoyama T., Takahashi M.

Gait and Posture (Gait and Posture) 65 176 - 181 2018.09

ISSN 09666362

© 2018 Background: Lumbopelvic pain (LPP) is one of the most common discomforts during pregnancy. However, few studies have evaluated relation between LPP and gait in pregnancy quantitatively. Research question: This study aimed to investigate the relation between the LPP and gait characteristics such as symmetry, stability, and the degree of motion during pregnancy. Methods: Gait data were collected for fifty-two pregnant women between the third and tenth month of pregnancy on smooth, horizontal walkway by using inertial measurement sensor units attached to the participants’ lumbar. The degrees of trunk movement, movement symmetry, gait variability, and symmetry of rotation were expressed as the root mean square (RMS), autocorrelation peak (AC), coefficient of variance (CV), and the degree of asymmetry at the approximate amount of angular variation (DA) respectively, which were calculated from measured acceleration data and angular velocity data. An independent t-test was performed to investigate differences in these gait parameters between LPP group and pain free group classified according to the presence or absence of the pain, which is evaluated by using a questionnaire. In addition, LPP group was divided into 5 subgroups based on the types of pain, and the differences between the groups were also investigated by using a one way ANOVA. Results: Rotational asymmetry was observed in movement of the roll direction of the LPP patients. The DA of the roll angle of the LPP group was significantly greater than that in the pain free group (0.140 ± 0.093 vs. 0.077 ± 0.053, respectively; p = 0.004). In the analysis of pain complications, the significant difference in DA of roll angle, and CV of yaw angle were observed. Significance: The results indicated that motion asymmetry of both rotation and translation increased significantly in LPP patients’ gait.

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Inverted Rearfoot posture in subjects with coexisting patellofemoral osteoarthritis in medial knee osteoarthritis: An exploratory study

Iijima H., Ohi H., Fukutani N., Aoyama T., Kaneda E., Abe K., Takahashi M., Matsuda S.

Journal of Foot and Ankle Research (Journal of Foot and Ankle Research) 11 ( 1 ) 2018.05

© 2018 The Author(s). Background: While abnormal rearfoot posture and its relationship to patellofemoral (PF) pain has been thoroughly discussed in the literature, its relationship to patellofemoral osteoarthritis (PFOA) has not been determined. This study aimed to examine whether rearfoot posture is associated with a higher prevalence of radiographic PFOA in a compartment-specific manner in patients with medial tibiofemoral osteoarthritis (TFOA). Methods: Participants from orthopedic clinics (n=68, age 56-90 years, 75.0% female), diagnosed with radiographic medial TFOA (Kellgren/Lawrence [K/L] grade≥2) were included in this study. The presence of PFOA and static rearfoot posture were evaluated using a radiographic skyline view and a footprint automatic measurement apparatus, respectively. The relationship between rearfoot posture and PFOA was examined using analysis of covariance and propensity score-adjusted logistic regression analysis. Results: On average, patients with coexisting PFOA and medial TFOA (n=39) had an inverted calcaneus 3.1° greater than those with isolated medial TFOA (n=29). Increased calcaneus inverted angle was significantly associated with a higher probability of the presence of medial PFOA (odds ratio: 1.180, 95% confidence interval: [1.005, 1.439]; p=0.043). Calcaneus inverted angle was not associated with higher odds of lateral PFOA presence based on the adjusted values. Conclusions: The presence of an inverted rearfoot was associated with PFOA. Although these findings do not clearly indicate a biomechanical link between rearfoot posture and PFOA, this study shed light on the potential relationship between altered rearfoot posture and PFOA, as can be seen between rearfoot abnormality and PF pain.

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Comparison of the Effects of Kilohertz- and Low-frequency Electric Stimulations: A Systematic Review with Meta-analysis

Hirotaka Iijima, TAKAHASHI MASAKI, Yuta Tashiro, Tomoki Aoyama

PLOS ONE (PLoS ONE) 13 ( 4 ) 2018.04

Research paper (scientific journal), Joint Work, Accepted

© 2018 Iijima et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Objective This study aimed to determine whether kilohertz-frequency alternating current (KFAC) is superior to low-frequency pulsed current (PC) in increasing muscle-evoked torque and lessening discomfort. Data sources The electronic databases PubMed, PEDro, CINAHL, and CENTRAL were searched for related articles, published before August 2017. Furthermore, citation search was performed on the original record using Web of Science. Review methods Randomized controlled trials, quasi-experimental studies, and within-subject repeated studies evaluating and comparing KFAC and PC treatments were included. The pooled standardized mean differences (SMDs) of KFAC and PC treatments, with 95% confidence intervals (CIs), were calculated using the random effects model. Results In total, 1148 potentially relevant articles were selected, of which 14 articles with within-subject repeated designs (271 participants, mean age: 26.4 years) met the inclusion criteria. KFAC did not significantly increase muscle-evoked torque, compared to PC (pooled SMD: -0.25; 95% CI: -0.53, 0.06; P = 0.120). KFAC had comparable discomfort compared to that experienced using PC (pooled SMD: -0.06; 95% CI: -0.50, 0.38; P = 0.800). These estimates of the effects had a high risk of bias, as assessed using the Downs and Black scale, and were highly heterogeneous studies. Conclusions This meta-analysis does not establish that KFAC is superior to PC in increasing muscle-evoked torque and lessening discomfort level. However, no strong conclusion could be drawn because of a high risk of bias and a large amount of heterogeneity. High quality studies comparing the efficacy between PC and KFAC treatments with consideration of potential confounders is warranted to facilitate the development of effective treatment.

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Pelvic alignment risk factors correlated with sacroiliac joint pain during pregnancy

Saori Morino, Mika Ishihara, Fumiko Umezaki, Hiroko Hatanaka, Mamoru Yamashita, Tomoki Aoyama, TAKAHASHI MASAKI

Clinical and Experimental Obstetrics & Gynecology 2018.04

Research paper (scientific journal), Joint Work, Accepted

Low back pain and causative movements in pregnancy: a prospective cohort study

Saori Morino, Mika Ishihara, Fumiko Umezaki, Hiroko Hatanaka, Hirotaka Iijima, Mamoru Yamashita, Tomoki Aoyama, TAKAHASHI MASAKI

BMC Musculoskeletal Disorders 2018.04

Research paper (scientific journal), Joint Work, Accepted

Effectiveness of Mesenchymal Stem Cells for Treating Patients with Knee Osteoarthritis: A Meta-analysis toward the Establishment of Effective Regenerative Rehabilitation

Hirotaka Iijima, Takuya Isho, Hiroshi Kuroki, TAKAHASHI MASAKI, Tomoki Aoyama

npj(nature partner journals) Regenerative Medicine (npj Regenerative Medicine) 3 ( 1 ) 2018.04

Research paper (scientific journal), Joint Work, Accepted

© 2018, The Author(s). This systematic review with a meta-analysis aimed to summarize the current evidence of the effectiveness of mesenchymal stem cell (MSC) treatment for knee osteoarthritis (OA) and to examine whether rehabilitation is an effect modifier of the effect estimate of MSC treatment. A literature search yielded 659 studies, of which 35 studies met the inclusion criteria (n = 2385 patients; mean age: 36.0–74.5 years). The meta-analysis results suggested that MSC treatment through intra-articular injection or arthroscopic implantation significantly improved knee pain (standardized mean difference [SMD]: −1.45, 95% confidence interval [CI]: −1.94, −0.96), self-reported physical function (SMD: 1.50, 95% CI: 1.09, 1.92), and cartilage quality (SMD: −1.99; 95% CI: −3.51, −0.47). However, the MSC treatment efficacy on cartilage volume was limited (SMD: 0.49; 95% CI: −0.19, 1.16). Minor adverse events (knee pain or swelling) were reported with a wide-ranging prevalence of 2–60%; however, no severe adverse events occurred. The evidence for these outcomes was “very low” to “low” according to the Grades of Recommendation, Assessment, Development and Evaluation system because of the poor study design, high risk of bias, large heterogeneity, and wide 95% CI of the effects estimate. Performing rehabilitation was significantly associated with better SMD for self-reported physical function (regression coefficient: 0.881, 95% CI: 0.049, 1.712; P = 0.039). We suggest that more high quality randomized controlled trials with consideration of the potential rehabilitation-driven clinical benefit would be needed to facilitate the foundation of effective MSC treatment and regenerative rehabilitation for patients with knee OA.

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Effects of Kilohertz-Frequency Electrical Stimulation on Muscle Performance and Adverse Event in Individuals with Neuromuscular Skeletal Disorders: A Systematic Review

Iijima H, TAKAHASHI MASAKI, Tashiro Y, Aoyama

The Japanese Journal of Rehabilitation Medicine 2018.04

Research paper (scientific journal), Joint Work, Accepted

ベクタリングによる管制間隔の調整と騒音の広域分担を目的とした着陸航空機の軌道計画

杉原有理花, 髙橋正樹

日本航空宇宙学会論文集 (日本航空宇宙学会) 66 ( 2 ) 53 - 60 2018.04

Research paper (scientific journal), Joint Work, Accepted

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慣性センサを用いた妊婦の腰椎骨盤周囲痛に関連する体幹部の動作解析

森野佐芳梨, 髙橋正樹

日本機械学会論文集 (日本機械学会) 84 ( 859 ) 01 - 13 2018.03

Research paper (scientific journal), Joint Work, Accepted

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Biomechanical characteristics of stair ambulation in patients with knee OA: A systematic review with meta-analysis toward a better definition of clinical hallmarks

Hirotaka Iijima, Kanako Shimourab, Tomoki Aoyama, TAKAHASHI MASAKI

Gait & Posture (Gait and Posture) 62 191 - 201 2018.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 09666362

© 2018 Elsevier B.V. Background: Stair climbing was suggested to be the first affected task in individuals with knee osteoarthritis (OA). Research question: This review aimed to identify consistent kinematic, kinetic, and spatiotemporal alterations of stair climbing exhibited by individuals with knee OA. Methods: A literature search published until September 2017 was conducted in PubMed, PEDro, CINAHL, and Cochrane CENTRAL. Reviewer extracted data in accordance with the Cochrane Handbook. Where possible, data were combined into a meta-analysis; the pooled standardized mean differences between individuals with knee OA and healthy adults were calculated using the random-effect model. Results: In total, 585 potentially relevant articles were selected, of which 12 (695 participants, mean age: 58.4 years) met the inclusion criteria. Meta-analysis revealed that kinematic and kinetic alterations during stair climbing associated with knee OA were lower external knee flexion moment in conjunction with a larger trunk/hip flexion angles and smaller knee flexion/ankle dorsiflexion angles. Individuals with knee OA showed a delayed quadriceps activation during stair ascent. A lack of evidence was detected for alterations in external knee adduction moment during stair climbing. Effect estimate in each meta-analysis was judged “very low” on the GRADE approach. Significance: No strong conclusion can be drawn because of the low quality of evidence; however, individuals with knee OA may exhibit altered kinematics and kinetics changes in sagittal plane during stair climbing, and have delayed quadriceps muscle activity. Further studies with adequate adjustment for confounders are warranted to facilitate clinical hallmarks of the knee OA, particularly in early stages of the disease.

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Validity of the Nintendo Wii Balance Board for Kinetic Gait Analysis

Ryo Eguchi, TAKAHASHI MASAKI

Applied Sciences (Applied Sciences (Switzerland)) 8 ( 25 ) 2018.02

Research paper (scientific journal), Joint Work, Accepted

© 2018 by the authors. The Nintendo Wii Balance Board (WBB) has been suggested as an inexpensive, portable and accessible alternative to costly laboratory-grade force plates for measuring the vertical ground reaction force (vGRF) and center of pressure (COP). Kinetic gait analysis provides important information for the rehabilitation of patients with gait disorders; however, the validity of the WBB for measuring kinetic gait parameters has not been evaluated. Therefore, the purpose of this study is to determine the accuracy of walking force measurements-which change dynamically in a short period of stance time-collected with the WBB. Three healthy adults were asked to walk 10 steps along both straight and curved paths in clockwise (CW) and counterclockwise (CCW) directions while measurements were taken using the WBB and the force plate. The accuracy of the vGRF, COP trajectory, and stance duration were evaluated using the root-mean-square error (RMSE), Pearson's correlation coefficient and Bland-Altman plots (BAPs) to compare the WBB and the force plate. The results of the vGRF showed high accuracy (r > 0.96 and %RMSE < 6.1% in the mean values), and the stance duration as defined by the vGRF and COP trajectory was equivalent to that of commercial instrumented insoles, which are used as an alternative to the force plates. From these results, we determined that the WBB may be used for kinetic gait analysis in clinical settings where lower accuracy is acceptable.

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Driving Control of a Powered Wheelchair Considering Uncertainty of Gaze Input in Unknown Environment

Airi Ishizuka, Ayanori Yorozu, TAKAHASHI MASAKI

Applied Sciences (Applied Sciences (Switzerland)) 8 ( 2 ) 2018.02

Research paper (scientific journal), Joint Work, Accepted

© 2018 by the authors. This paper describes the motion control system for a powered wheelchair using eye gaze in an unknown environment. Recently, new Human-Computer Interfaces (HCIs) that have replaced joysticks have been developed for a person with a disability of the upper body. In this paper, movement of the eyes is used as an HCI. The wheelchair control system proposed in this study aims to achieve an operation such that a passenger gazes towards the direction he or she wants to move in the unknown environment. Implementation of such an operating method facilitates easy and accurate movement of the wheelchair even in complicated environments comprising passages on the same side. This paper presents a system based on gaze detection and environment recognition that are integrated by the fuzzy set theory in real time. In the fuzzy set theory, we achieve the movement to the passage which a passenger gazes towards among some passages by integrating the information of some passages and gaze. Moreover, we design it with consideration of uncertain gaze input by using the value of gaze detection accuracy. Moreover, we achieve obstacle avoidance by integrating the information of obstacles. This motion control system can support safe and smooth movement of the wheelchair by automatically calculating its direction of motion and velocity, to avoid obstacles and move in the gaze direction of the passenger. The effectiveness of the proposed system is demonstrated through experiments in a real environment.

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Accessible ground reaction force estimation using insole force sensors without force plates

Eguchi R., Yorozu A., Takahashi M.

2017 Asian Control Conference, ASCC 2017 (2017 Asian Control Conference, ASCC 2017) 2018-January 2861 - 2865 2018.02

ISSN 9781509015733

© 2017 IEEE. Ground reaction force (GRF) estimations using instrumented insoles relied on the use of costly force plates in previous works. This paper designed insoles with 15 force sensing resisters and presents an accessible estimation method of vertical GRF (vGRF) using the insole without any cost-prohibitive devices. To determine vGRF from the insole sensor forces, a subject-specific linear regression model was constructed using a least-squares method with a constraint and a bound. The regression matched the sensor forces during single-leg standing (SLS) to a subject's body weight with a linear constraint using data measured while walking. During SLS, standing static and shifting body weight were performed to enhance estimation accuracies. The accuracies of constructed models while walking were evaluated by comparison with the Nintendo Wii Balance Board (WBB) which can measure accurate vGRF compared with force plates. The results for an adult had 8-15 % root mean squared errors (RMSEs) with no significant deviations from previous methods which relied on force plates. From these results, the proposed method was validated as an accessible kinetic gait analysis system.

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Simultaneous dual-arm motion planning considering shared transfer path for minimizing operation time

Kurosu J., Yorozu A., Takahashi M.

2017 Asian Control Conference, ASCC 2017 (2017 Asian Control Conference, ASCC 2017) 2018-January 467 - 472 2018.02

ISSN 9781509015733

© 2017 IEEE. One of the most basic tasks that a dual-arm robot does is pick-up and place work. Pick-up and place work consists of tasks in which the robot carries objects from a start position (initial position) to a goal position. The following three important points should also be considered when the dual-arm robot does this work efficiently: 1) collision avoidance of the arms, 2) which arm should move an object, and 3) the order in which the objects should be picked up and placed. In addition, dual-arm robot has operation range constraints. Depending on the position relationship between a start position and goal position, unless both arms are used, the object may not be transferred to a goal position. In this paper, we define the transfer path which must use both arms as 'shared transfer path'. Therefore, we propose a motion planning method to achieve efficient pick-up and place work considering shred transfer path. First, we use mixed integer linear programming (MILP) based planning for the pick-up and place work to determine which arm should move an object and in which order these objects should be moved while considering the dual-arm robot's operation range. Second, we plan the path using the rapidly exploring random tree (RRT) so that the arms do not collide, enabling the robot to perform efficient pick-up and place work based on the MILP planning solution. The effectiveness of proposed method is confirmed by simulations and experiments using the HIRO dual-arm robot.

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Motion control of a powered wheelchair using eye gaze in unknown environments

Ishizuka A., Yorozu A., Takahashi M.

2017 Asian Control Conference, ASCC 2017 (2017 Asian Control Conference, ASCC 2017) 2018-January 90 - 95 2018.02

ISSN 9781509015733

© 2017 IEEE. This paper describes the motion control system for a powered wheelchair using eye gaze in an unknown environment. Recently, new Human-Computer Interfaces (HCIs) that have replaced joysticks have been developed for a person with a disability of the upper body. In this paper, movement of the eyes is used as an HCI. The wheelchair control system proposed in this study aims to achieve an operation such that a passenger gazes towards the direction he or she wants to move in the unknown environment. This paper presents a system based on gaze detection and environment recognition that are integrated by the fuzzy set theory in real time. This motion control system can support safe and smooth movement of the wheelchair by automatically calculating its direction of motion and velocity, to avoid obstacles and move in the gaze direction of the passenger. The effectiveness of the proposed system is demonstrated through experiments in a real environment.

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Attitude Maneuver and Gimbal angle guidance by SDRE controller using SGCMG integrated satellite SDLR model

Ozawa R., Takahashi M.

2017 Asian Control Conference, ASCC 2017 (2017 Asian Control Conference, ASCC 2017) 2018-January 1847 - 1852 2018.02

ISSN 9781509015733

© 2017 IEEE. In the conventional agile attitude maneuver of a satellite, a control system of the satellite and Single Gimbal Control Moment Gyro (SGCMG) is designed separately and stability is not guaranteed under the singularity of SGCMGs. Therefore, in this research, we integrate the satellite and SGCMGs and design a model with the gimbal angular velocity as input. Since the target gimbal angle can be explicitly designed by a null motion, proposed control system is possible to guide the initial gimbal angle which is advantageous for next mission. In addition, it is shown that proposed method can guarantee stability even under the singularity of SGCMGs by the State-Dependent Riccati Equation (SDRE). Moreover, numerical simulations show that the singularity avoidance performance up to the target gimbal angle and the guidance performance of the gimbal angle are higher than the conventional method due to the optimality of gimbal angular velocity input.

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Agile Attitude Control and Singularity avoidance/escaping by SDRE Method using Biased State-Dependent Weighting Matrix

Ryotaro Ozawa, TAKAHASHI MASAKI

Applied Sciences (Applied Sciences (Switzerland)) 8 ( 1 ) 2018.01

Research paper (scientific journal), Joint Work, Accepted

© 2016 by the authors. In recent years there has been an increasing need to improve satellite attitude control performance in terms of agility and attitude accuracy in large-angle attitude maneuvers. To achieve such control performance, single-gimbal control moment gyros (SGCMGs) should be mounted as modern-type actuators. Conventionally, based on the torque command calculated by the attitude control system of the satellite, SGCMGs were controlled by solving inverse kinematics through a pseudo inverse matrix steering law. However, in such a control system structure, it may be difficult to obtain the desired torque required by the attitude control system because of the singularity problem of SGCMGs. Furthermore, with respect to implementation, since the condition number of the Jacobian matrix of SGCMG becomes extremely large in the singularity, the numerical calculation error of the pseudo inverse matrix increases greatly. Therefore, we propose an overall control system that can solve above-described problems and the state-dependent Riccati equation (SDRE) control system that integrates the satellite and SGCMG system. The proposed optimal control system, which does not solve the pseudo inverse matrix, can realize gimbal angle guidance by gimbal angle feedback and singularity avoidance/escape using the biased weighting matrix. In the numerical simulation, the usefulness of proposed system is shown in comparison with the conventional system.

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Optimal Sizing of Energy Storage Systems for the Energy Procurement Problem in Multi-period Markets under Uncertainties

Ryusuke Konishi, Akiko Takeda, TAKAHASHI MASAKI

Energies (Energies) 11 ( 1 ) 1 - 19 2018.01

Research paper (scientific journal), Joint Work, Accepted

© 2018 by the authors. In deregulated electricity markets, minimizing the procurement costs of electricity is a critical problem for procurement agencies (PAs). However, uncertainty is inevitable for PAs and includes multiple factors such as market prices, photovoltaic system (PV) output and demand. This study focuses on settlements in multi-period markets (a day-ahead market and a real-time market) and the installation of energy storage systems (ESSs). ESSs can be utilized for time arbitrage in the day-ahead market and to reduce the purchasing/selling of electricity in the real-time market. However, the high costs of an ESS mean the size of the system needs to be minimized. In addition, when determining the size of an ESS, it is important to identify the size appropriate for each role. Therefore, we employ the concept of a "slow" and a "fast" ESS to quantify the size of a system's role, based on the values associated with the various uncertainties. Because the problem includes nonlinearity and non-convexity, we solve it within a realistic computational burden by reformulating the problem using reasonable assumptions. Therefore, this study identifies the optimal sizes of ESSs and procurement, taking into account the uncertainties of prices in multi-period markets, PV output and demand.

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Agile attitude maneuver via SDRE controller using SGCMG integrated satellite model

Ozawa R., Takahashi M.

AIAA Guidance, Navigation, and Control Conference, 2018 (AIAA Guidance, Navigation, and Control Conference, 2018) ( 210039 ) 2018.01

ISSN 9781624105265

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. In this research, we propose a design method for a nonlinear optimal attitude control system that combines the systems of a single-gimbal control moment gyro (SGCMG) and a satellite that were conventionally designed separately. For this purpose, we designed a state-dependent linear representation model integrating satellite dynamics and SGCMG dynamics using a State-Dependent Riccati Equation (SDRE) controller. In the proposed method, it is possible to design the gimbal angular velocity as input without solving the inverse kinematics in the pyramid-type SGCMG. Therefore, it is possible to avoid the singularity of SGCMG by designing the weighting function matrices considering the relationship between the maneuvering axis and SGCMG steering. A numerical simulation shows that it is possible to achieve a high-speed attitude maneuver of the satellite by optimal attitude control considering singularity avoidance by the proposed method. In addition, usefulness of proposed law is shown in comparison with the GSR Inverse steering logic for the agile attitude maneuver.

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Control system design of a quadrotor moderating the virtual reality sickness

Watanabe K., Takahashi M.

AIAA Modeling and Simulation Technologies Conference, 2018 (AIAA Modeling and Simulation Technologies Conference, 2018) ( 209959 ) 2018

ISSN 9781624105289

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Camera-mounted quadrotor is currently being utilized as teleoperation robot for search and rescue purposes. However, controlling a quadrotor with proportional R/Cs in remote is not intuitive. Thus, combination with Head Mount Display (HMD) is proposed to increase the ease of maneuverability and sense of immersion. However, it has been reported that the video that contains vibration may induce virtual reality (VR) sickness. Particularly, a quadrotor can largely be disturbed by the wind causing the video to oscillate. Our experiment implies that the large amplitude of vibration and low frequency may have effect on inducing VR sickness. This study investigates the effect of a certain frequency of vibration to VR sickness, and proposes the attitude control of a quadrotor to avoid such movement which may induce sickness.

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Postpartum radiographic changes in pelvic morphology and its relation with symptoms of pregnancy-related symphysis pain

Ji X., Takahashi M., Morino S., Takakuwa T., Iijima H., Zhang X., Ishihara M., Kawagoe M., Hatanaka Y., Umezaki F., Yamashita M., Tsuboyama T., Aoyama T.

Clinical and Experimental Obstetrics and Gynecology (Clinical and Experimental Obstetrics and Gynecology) 45 ( 5 ) 665 - 670 2018

ISSN 03906663

© 2018 S.O.G. CANADA Inc. All rights reserved. Introduction: The etiology of pregnancy-related pubic symphysis pain (PSP) is usually considered as the change in pelvic biomechanics during pregnancy. However, the biomechanical changes that occur during puerperium, and the difference of radiographic dimensions in women with different types of PSP remains unknown. Materials and Methods: Fifty women with self-reported PSP were included. Two conventional X-ray radiographic dimensions obtained on the delivery day and one-month postpartum were compared by using paired t-test. Based on the self-reported VAS at one-month postpartum, variables between pain-recovery and non-recovery groups were also compared. Results: The comparison between pre- and post-values indicates a reduced distance between FLAMs (239.1 vs. 237.0 mm), PS separation (7.9 vs. 6.5 mm), and PS translation (4.1 vs. 3.1 mm). No significant differences were observed in the distance between FLAMs, width of PS separation, or pubic symphysial surface (PSS) angle between the recovery and non-recovery groups. However, the non-recovery group exhibited a significantly large change in PS translation at one-month postpartum than the recovery group (-1.8 vs. -1.1 mm). Conclusions: The pelvic radiography demonstrated a 'closure' alteration in the pelvic cavity diameter one-month postpartum with a decrease in the distance between FLAMs and shortened PS separation. The difference in radiographic diameters between groups was not clearly evident.

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Pelvic alignment risk factors associated with sacroiliac joint pain during pregnancy

Morino S., Ishihara M., Umezaki F., Hatanaka H., Yamashita M., Aoyama T., Takahashi M.

Clinical and Experimental Obstetrics and Gynecology (Clinical and Experimental Obstetrics and Gynecology) 45 ( 6 ) 850 - 854 2018

ISSN 03906663

© 2018 S.O.G. Canada Inc.All rights reserved. Purpose of investigation: To investigate the influence of the change in pelvic alignment during pregnancy on sacroiliac joint pain (SIJP). Materials and Methods: Participants included 168 women without SIJP at recruitment and were evaluated at 12 and 36 weeks of pregnancy. SIJP intensity was assessed using the Numerical Rating Scale (NRS). Pelvic alignment measurements included the anterior and posterior width of the pelvis, anterior pelvic tilt, and pelvic asymmetry. Participants were divided into the SIJP and non-SIJP groups based on the presence of SIJP at 36 weeks of pregnancy. The influence of the change in pelvic alignment during pregnancy between the groups was investigated. Results: The amount of change in pelvic anteversion during pregnancy was smaller and the change in pelvic asymmetry was significantly greater in the SIJP group compared to that in the non-SIJP group. In addition, an increase in pelvic asymmetry was the most strongly associated risk factor for SIJP. Conclusions:A forward-bending pelvis in early pregnancy and an increase in pelvic asymmetry during pregnancy are risk factors for pregnancy-related SIJP.

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Minimum-time attitude maneuver of small satellite mounted with communication antenna

Mori K., Takahashi M.

Space Flight Mechanics Meeting, 2018 (Space Flight Mechanics Meeting, 2018) ( 210009 ) 2018

ISSN 9781624105333

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This paper proposes a simultaneous control method for small satellites mounted with a communication antenna; the objective is to reduce the time involved in satellite maneuver and antenna motion. Recently, small Earth observation satellites have been utilized, even though agile large angle satellite attitude maneuver has been in demand. Small Earth observation satellites acquire high-resolution data, resulting in an increase in the time required for data communication. Therefore, it has become important to ensure that small Earth observation satellites are capable of being maneuvered rapidly so that communication time can be extended by using a data relay system. In conventional operations, the antenna motion is implemented after satellite attitude maneuver. However, this method has a time delay between the completion of the attitude maneuver and the start of data communication. The purpose of this study is to extend the time for Earth observation and data communication. In order to achieve this, we propose a simultaneous control method for satellite maneuver and antenna motion using a nonlinear programming problem.

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Simultaneous Dual-Arm Motion Planning for Minimizing Operation Time

Jun Kurosu, Ayanori Yorozu, TAKAHASHI MASAKI

Applied Sciences 7 ( 12 ) 2017.12

Research paper (scientific journal), Joint Work, Accepted

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Markerless Knee Joint Position Measurement Using Depth Data during Stair Walking

Ami Ogawa, Akira Mita, Ayanori Yorozu, TAKAHASHI MASAKI

Sensors 17 ( 11 ) 2017.11

Research paper (scientific journal), Joint Work, Accepted

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Estimating co-contraction activation of trunk muscles using a novel musculoskeletal model for pregnant women

Saori Morino, TAKAHASHI MASAKI

Applied Sciences 7 ( 10 ) 2017.10

Research paper (scientific journal), Joint Work, Accepted

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Optimal Allocation of Photovoltaic Systems and Energy Storage Systems based on Vulnerability Analysis

Ryusuke Konishi, TAKAHASHI MASAKI

Energies 1 ( 9 ) 305 - 313 2017.10

Research paper (scientific journal), Joint Work, Accepted

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複数レーザレンジセンサを用いた高精度歩行計測システム（高齢者のTimed Up and Go試験への適用）

萬礼応, 髙橋正樹

日本機械学会論文集 (日本機械学会) 85 ( 855 ) 01 - 17 2017.09

Research paper (scientific journal), Joint Work, Accepted

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Association between mild cognitive impairment and trajectory-based spatial parameters during timed up and go test using a laser range sensor

Shu Nishiguchi, Ayanori Yorozu, Daiki Adachi, TAKAHASHI MASAKI, Tomoki Aoyama

Journal of NeuroEngineering and Rehabilitation 1 ( 9 ) 305 - 313 2017.08

Research paper (scientific journal), Joint Work, Accepted

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SVM-based Multi-point Prediction System of Solar Irradiance using DTW-based Cluster Analysis

Yukiya Tanaka, TAKAHASHI MASAKI

Transactions of the Institute of Systems, Control and Information Engineers 61 ( 8 ) 305 - 313 2017.08

Research paper (scientific journal), Joint Work, Accepted

Generating linear regression model to predict motor functions by use of laser range finder during TUG

Daiki Adachi, Shu Nishiguchi, Naoto Fukutani, Takayuki Hotta, Yuto Tashiro, Saori Morino, Hidehiko Shirooka, Yuma Nozaki, Hinako Hirata, Moe Yamaguchi, Ayanori Yorozu,, TAKAHASHI MASAKI, Tomoki Aoyama

Journal of Orthopaedic Science 22 ( 3 ) 549 - 553 2017.05

Research paper (scientific journal), Joint Work, Accepted

Mode-scheduling Steering Law of VSCMGs for Multi-target Pointing and Agile Maneuver of a Spacecraft

Yasuyuki Nanamori, TAKAHASHI MASAKI

International Journal of Advanced Computer Science and Applications (The Science and Information Organization) 8 ( ５ ) 25 - 34 2017.05

Research paper (scientific journal), Joint Work, Accepted

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Association of Lumbopelvic Pain with Pelvic Alignment and Gait Pattern during Pregnancy

Saori Morino, TAKAHASHI MASAKI, Ayumi Tanigawa, Shu Nishiguchi, Naoto, Fukutani, Daiki Adachi,Yuto Tashiro, Takayuki Hotta, Daisuke Matsumoto, Tomoki Aoyama

Journal of Women’s Health 6 ( 2 ) 1 - 5 2017.05

Research paper (scientific journal), Joint Work, Accepted

VSCMG搭載宇宙機における姿勢制御とバッテリーの長寿命化を考慮した電力マネジメント

七森泰之, 髙橋正樹

日本航空宇宙学会論文集 (日本航空宇宙学会) 65 ( 2 ) 95 - 102 2017.04

Research paper (scientific journal), Joint Work, Accepted

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Model-based Pedestrian Trajectory Prediction using Environmental Sensor for Mobile Robots Navigation

Haruka Tonoki, Ayanori Yorozu, TAKAHASHI MASAKI

International Journal of Advanced Computer Science and Applications (The Science and Information Organization) 8 ( 2 ) 95 - 101 2017.02

Research paper (scientific journal), Joint Work, Accepted

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Optimal Facility Allocation and Determination of Demand Response Participation Rate Considering Uncertainties in Power Systems

Ryusuke Konishi, TAKAHASHI MASAKI

Transactions of the Institute of Systems, Control and Information Engineers (Institute of Systems, Control and Information Engineers) 30 ( 1 ) 10 - 19 2017.01

Research paper (scientific journal), Joint Work, Accepted

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Path Planning to Improve Reachability in a Forced LandingAutonomous Mobile Robot

Shunsuke Izuta, TAKAHASHI MASAKI

Journal of Intelligent and Robotic Systems (Springer) 86 ( 2 ) 291 - 307 2016.10

Research paper (scientific journal), Joint Work, Accepted

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Obstacle Avoidance with Translational and Efficient Rotational Motion Control Considering Movable Gaps and Footprint for Autonomous Mobile Robot

Ayanori Yorozu, TAKAHASHI MASAKI

International Journal of Control, Automation and Systems (Springer) 14 ( 5 ) 1352 - 1364 2016.07

Research paper (scientific journal), Joint Work, Accepted

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衝突被害軽減のための乗員挙動を考慮した自動車の時変ゲイン型減速度制御

太刀川健, 髙橋正樹

日本機械学会論文集 (日本機械学会) 82 ( 837 ) 1 - 16 2016.05

Research paper (scientific journal), Joint Work, Accepted

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Dynamics-Based Nonlinear Acceleration Control With Energy Shaping for a Mobile Inverted Pendulum With a Slider Mechanism

Kazuto Yokoyama, TAKAHASHI MASAKI

Transactions on Control System Technology (IEEE) 24 ( 1 ) 40 - 55 2016.01

Research paper (scientific journal), Joint Work, Accepted, ISSN 1063-6536

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Long-range navigation for resource-constrained planetary rovers using angle of arrival

Takayuki Ishida, Hiroka Inoue, Wataru Mogi, TAKAHASHI MASAKI, Masahiko Ono, Shuichi Adachi

Mechanical Engineering Journal (The Japan Society of Mechanical Engineers) 2 ( 6 ) 1 - 10 2015.10

Research paper (scientific journal), Joint Work, Accepted

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Improved Leg Tracking Considering Gait Phase and Spline-based Interpolation during Turning Motion in Walk Tests

Ayanori Yorozu, TAKAHASHI MASAKI

Sensors 15 ( 9 ) 22451 - 22472 2015.09

Research paper (scientific journal), Joint Work, Accepted

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コントロールモーメントジャイロ搭載宇宙機の耐故障姿勢制御系

能美亜衣, 髙橋正樹

日本機械学会論文集 (日本機械学会) 81 ( 826 ) 1 - 13 2015.06

Research paper (scientific journal), Joint Work, Accepted

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Gait Measurement System for the Multi-Target Stepping Task Using a Laser Range Sensor

Ayanori Yorozu, Shu Nishiguchi, Minoru Yamada, Tomoki Aoyama, Toshiki Moriguchi, TAKAHASHI MASAKI

Sensors 15 ( 5 ) 11151 - 11168 2015.05

Research paper (scientific journal), Joint Work, Accepted

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Dynamics-Based Nonlinear Acceleration Control With Energy Shaping for a Mobile Inverted Pendulum With a Slider Mechanism

Kazuto Yokoyama, TAKAHASHI MASAKI

IEEE Transactions on Control System Technology (The Science and Information Organization) 1 - 16 2015.04

Research paper (scientific journal), Joint Work, Accepted

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レーザレンジセンサを用いた片足立ち時間計測（高齢者の転倒危険度評価システムのための運動機能評価）

萬礼応, 森口智規, 並川浩史, 髙橋正樹

日本機械学会論文集 (日本機械学会) 81 ( 824 ) 1 - 12 2015.04

Research paper (scientific journal), Joint Work, Accepted

セミアクティブダンパの減衰特性を考慮した最適制御系設計

石崎樹, 髙橋正樹

日本機械学会論文集 (日本機械学会) 81 ( 823 ) 1 - 10 2015.03

Research paper (scientific journal), Joint Work, Accepted

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Fault-Tolerant Attitude Control System for a Spacecraft with Control Moment Gyros Using Multi-Objective Optimization

Ai Noumi, Misuzu Haruki, Takuya Kanzawa, TAKAHASHI MASAKI

Journal of Advanced Computer Science and Applications (The Science and Information Organization) 6 ( 1 ) 40 - 48 2015.01

Research paper (scientific journal), Joint Work, Accepted

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Human-centered X–Y–T space path planning for mobile robot in dynamic environments

Ippei Nishitani, Tetsuya Matsumura, Mayumi Ozawa, Ayanori Yorozu, TAKAHASHI MASAKI

Robotics and Autonomous Systems (Elsevier) 66 18 - 26 2015.01

Research paper (scientific journal), Joint Work, Accepted

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Energy shaping non-linear acceleration control for a pendulum-type mobility and experimental verification

Kazuto Yokoyama, TAKAHASHI MASAKI

Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility (Taylor & Francis) 53 ( 2 ) 179 - 196 2015.01

Research paper (scientific journal), Joint Work, Accepted

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Attitude determination of planetary exploration rovers using solar panels characteristics and accelerometer

Takayuki Ishida, TAKAHASHI MASAKI

Acta Astronautica (Elsevier) 105 ( 1 ) 344 - 354 2014.10

Research paper (scientific journal), Joint Work, Accepted

随意性瞬目を用いた電動車いすの環境認識に基づく走行制御と実験的検証

奥川恭平, 中西正樹, 満倉靖恵, 髙橋正樹

日本機械学会論文集 (日本機械学会) 80 ( 813 ) 1 - 15 2014.05

Research paper (scientific journal), Joint Work, Accepted

Inverted Pendulum-type Personal Mobility Considering Human Vibration Sensitivity

Misaki Masuda, Takuma Suzuki, Kazuto Yokoyama, TAKAHASHI MASAKI

Journal of Advanced Computer Science and Applications (The Science and Information Organization) 5 ( 3 ) 189 - 195 2014.03

Research paper (scientific journal), Joint Work, Accepted

Gain-Scheduling H∞ Control to Improve Ride Comfort and Driving Stability for Vehicle Active Suspension

TAKAHASHI MASAKI, Shoichi Hiraoka, Takuma Suzuki

Vehicle Engineering (VE) 2 22 - 30 2014

Research paper (scientific journal), Joint Work, Accepted

環境情報を考慮した電動車椅子制御のための眼電位を用いた随意性瞬目検出手法

中西正樹, 奥川恭平, 髙橋　正樹, 満倉靖恵

電気学会論文誌C (電気学会) 133 ( 10 ) 1969 - 1975 2013.10

Research paper (scientific journal), Joint Work, Accepted

路面勾配の変化を考慮した倒立振子型移動体のモデル化と運動解析

菅野利昭, 横山和人, 鈴木卓馬, 髙橋正樹

日本機械学会論文集Ｃ編 (日本機械学会) 79 ( 801 ) 1441 - 1452 2013.05

Research paper (scientific journal), Joint Work, Accepted

レーザレンジファインダを用いた歩行計測システムの提案

小澤真裕美, 萬礼応, 松村哲哉, 髙橋正樹

日本機械学会論文集Ｃ編 (日本機械学会) 79 ( 801 ) 1550 - 1560 2013.05

Research paper (scientific journal), Joint Work, Accepted

コントロールモーメントジャイロ搭載人工衛星の角運動量経路計画による特異点回避

佐藤峻介, 髙橋正樹

日本機械学会論文集Ｃ編 (日本機械学会) 79 ( 801 ) 1526 - 1539 2013.05

Research paper (scientific journal), Joint Work, Accepted

Development of measurement system for task oriented step tracking using laser range finder

Tetsuya Matsumura, Toshiki Moriguchi, Minoru Yamada, Kazuki Uemura, Shu Nishiguchi, Tomoki Aoyama, TAKAHASHI MASAKI

Journal of NeuroEngineering and Rehabilitation (Springer) 10 ( 47 ) 1 - 8 2013.05

Research paper (scientific journal), Joint Work, Accepted

A novel infrared laser device that measures multilateral parameters of stepping performance for assessment of fall risk in elderly individuals

Shu Nishiguchi, Minoru Yamada, Kazuki Uemura, Tetsuya Matsumura, TAKAHASHI MASAKI, Toshiki Moriguchi, Tomoki Aoyama,

Aging Clinical and Experimental Research (Springer) 25 ( 3 ) 311 - 316 2013.05

Research paper (scientific journal), Joint Work, Accepted

最上層に制振装置を有する建物・エレベータ連成系の地震応答制御に関する振動台実験

WATANABE KEISUKE, MIURA NANAKO, KOHIYAMA MASAYUKI, TAKAHASHI MASAKI

構造工学論文集 59B 339 - 348 2013.03

Research paper (scientific journal), Joint Work, Accepted

操作入力と環境認識に基づく操作性の低いデバイスを利用する知的車いすの行動制御

ISHIHARA YU, TAKAHASHI MASAKI

日本ロボット学会誌 31 ( 1 ) 107 - 116 2013.01

Research paper (scientific journal), Joint Work, Accepted

Development of a Mobile Robot for Transport Application in Hospital, Journal of Robotics and Mechatronics

TAKAHASHI MASAKI, Toshiki Moriguchi, Shoji Tanaka, Hirofumi Namikawa, Hideo Shitamoto, Tsuyoshi Nakano, Yuichirou Minato, Takashi Ihama, Takahiko Murayama,

Journal of Robotics and Mechatronics 24 ( 6 ) 1046 - 1053 2012.12

Research paper (scientific journal), Joint Work, Accepted

エネルギー整形非線形制御による車体重心移動機構を有する倒立振子型移動体の不安定性を利用した加速制御

YOKOYAMA KAZUTO, TAKAHASHI MASAKI

日本機械学会論文集Ｃ編 (日本機械学会) 78 ( 794 ) 3469 - 3482 2012.10

Research paper (scientific journal), Joint Work, Accepted

Semi-Active Control for Isolated Structure Using Variable Damping Device Based on Response Evaluator of System

FUKUKITA AKIRA, TAKAHASHI MASAKI

Journal of System Design and Dynamics 6 ( 4 ) 511 - 524 2012.08

Research paper (scientific journal), Joint Work, Accepted

受動歩行を規範とした異なる重力環境下におけるコンパス型二足ロボットの歩行制御

MATSUMOTO YUSUKE, IKEDA TATSUHIKO, NARUKAWA TERUMASA, TAKAHASHI MASAKI

日本機械学会論文集Ｃ編 (日本機械学会) 78 ( 791 ) 2496 - 2508 2012.07

Research paper (scientific journal), Joint Work, Accepted

微小重力環境下における歩行特性解析に向けた追従式免荷装置の開発（リムレスホイールを用いた有効性の検証）

TAKAHASHI MASAKI

日本機械学会論文集C編 (日本機械学会) 78 ( 790 ) 2022 - 2033 2012.06

Research paper (scientific journal), Joint Work, Accepted

線形2次レギュレータを用いた建物・エレベータロープの分散協調制御手法の比較

YOSHIDA MINAKO, KOHIYAMA MASAYUKI, TAKAHASHI MASAKI

日本建築学会構造系論文集 77 ( 675 ) 705 - 714 2012.05

Research paper (scientific journal), Joint Work, Accepted

エネルギー整形非線形制御による倒立振子型移動体の不安定性を利用した加速制御

YOKOYAMA KAZUTO, TAKAHASHI MASAKI

日本機械学会論文集C編 (日本機械学会論文) 78 ( 788 ) 1097 - 1108 2012.04

Research paper (scientific journal), Joint Work, Accepted

車速による車両ダイナミクスの変化を考慮した自動車用アクティブサスペンションの制御系設計

鈴木卓馬, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 78 ( 786 ) 446 - 461 2012.02

Research paper (scientific journal), Joint Work, Accepted

Stabilization of a Mobile Inverted Pendulum with IDA-PBC and Experimental Verification

KAZUTO YOKOYAMA, TAKAHASHI MASAKI

Journal of System Design and Dynamics (JSME) 5 ( 8 ) 1605 - 1623 2011.12

Research paper (scientific journal), Joint Work, Accepted

Semi-Active Control for Base Isolated Structure Using Response Evaluator Subjected to Long-Period Earthquake Ground Motion

AKIRA FUKUKITA, TAKAHASHI MASAKI

Journal of System Design and Dynamics (JSME) 5 ( 8 ) 1674 - 1686 2011.12

Research paper (scientific journal), Joint Work, Accepted

可変剛性スタビライザを有するセミアクティブサスペンションシステム（第2報車両のロール剛性配分制御）

髙橋正樹, 小瀬村領一，平岡翔一，鈴木卓馬

日本機械学会論文集C編 (日本機械学会) 77 ( 784 ) 4434 - 4447 2011.12

Research paper (scientific journal), Joint Work, Accepted

Efficient Walking with Optimization for a Planar Biped Walker with a Torso by Hip Actuators and Springs

TERUMASA NARUKAWA, TAKAHASHI MASAKI, KAZUO YOSHIDA

Robotica (Robotica) 29 641 - 648 2011.11

Research paper (scientific journal), Joint Work, Accepted

Feedback Control with Nominal Inputs for Agile Satellite Using Control Moment Gyros

YOUICHIRO KUSUDA, TAKAHASHI MASAKI

AIAA Journal of Guidance, Navigation and Control (AIAA J GNC) 34 ( 4 ) 1209 - 1218 2011.07

Research paper (scientific journal), Joint Work, Accepted

Agile and Precise Attitude Switching Maneuver of Flexible Spacecraft based on Nonstationary Frequency-Shaped Robust Control, Journal of System Design and Dynamics

RYOTA IKEDA, TAKAHASHI MASAKI

Journal of System Design and Dynamics (JSME) 5 ( 5 ) 805 - 818 2011.07

Research paper (scientific journal), Joint Work, Accepted

Hierarchical Action Control Technique based on Prediction Time for Autonomous Omni-directional Mobile Robots

TAKAHASHI MASAKI, YOSHIMASA TADA, KAZUO YOSHIDA

Journal of System Design and Dynamics (JSME) 5 ( 4 ) 547-559 2011.06

Research paper (conference, symposium, etc.), Joint Work, Accepted

長周期地震動を受ける免震構造物の応答評価に基づくセミアクティブ制御

福喜多輝，髙橋正樹

日本機械学会論文集C編 (日本機械学会) 77 ( 777 ) 1649 - 1660 2011.05

Research paper (scientific journal), Joint Work, Accepted

IDA-PBCによる倒立振子型移動体の安定化制御と実機検証

横山和人，髙橋正樹

日本機械学会論文集C編 (日本機械学会) 77 ( 777 ) 1850 - 1865 2011.05

Research paper (scientific journal), Joint Work, Accepted

Semi-active Suspension Control System Design for Vibration Reduction of Passenger's Body based on Lissajous Figure of Damping Force

SUZUKI TAKUMA, TAKAHASHI MASAKI

Journal of System Design and Dynamics (JSME) 5 ( 2 ) 279 - 295 2011.03

Research paper (scientific journal), Joint Work, Accepted

Steering Law of Control Moment Gyros using Optimization of Initial Gimbal Angles for Satellite Attitude Control

NANAMORI YASUYUKI, TAKAHASHI MASAKI

Journal of System Design and Dynamics (JSME) 5 ( 1 ) 30 - 41 2011.01

Research paper (scientific journal), Joint Work, Accepted

Numerical and Experimental Studies of Planar Passive Biped Walker with Flat Feet and Ankle Springs

NARUKAWA TERUMASA, YOKOYAMA KAZUTO, TAKAHASHI MASAKI

Journal of System Design and Dynamics (JSME) 4 ( 6 ) 848 - 856 2010.12

Research paper (scientific journal), Joint Work, Accepted

先行車への追従性能と燃料消費の抑制を考慮した車間距離制御

三上佳彦, 髙橋正樹, 西村秀和, 久保田正博

日本機械学会論文集C編 (日本機械学会) 76 ( 772 ) 3549 - 3557 2010.12

Research paper (scientific journal), Joint Work, Accepted

自律全方位移動ロボットの並進と回転の同時制御によるロボットサイズを考慮した障害物回避

鈴木崇文, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 76 ( 772 ) 3567 - 3575 2010.12

Research paper (scientific journal), Joint Work, Accepted

路面入力に対する車両の平面運動を考慮した自動車用アクティブサスペンションの制御系設計

鈴木卓馬, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 76 ( 772 ) 3558 - 3566 2010.12

Research paper (scientific journal), Joint Work, Accepted

Stabilization of a Cart-Inverted Pendulum with Interconnection and Damping Assignment Passivity-Based Control Focusing on the Kinetic Energy Shaping

YOKOYAMA KAZUTO, TAKAHASHI MASAKI

Journal of System Design and Dynamics (JSME) 4 ( 5 ) 698 - 711 2010.10

Research paper (scientific journal), Joint Work, Accepted

Integrated Controller Design for Automotive Semi-Active Suspension Considering Vehicle Behavior with Steering Input

TAKAHASHI MASAKI, KUMAMARU TAKASHI, YOSHIDA KAZUO

Journal of System Design and Dynamics (JSME) 4 ( 5 ) 712 - 724 2010.10

Research paper (scientific journal), Joint Work, Accepted

Collision Avoidance of Hospital Autonomous Omni-directional Mobile Courier Robot System

TAKAHASHI MASAKI, SUZUKI TAKAFUMI, MORIGUCHI TOSHIKI, SHITAMOTO HIDEO, YOSHIDA KAZUO

Journal of Robotics and Autonomous Systems (IEEE) 58 ( 7 ) 889 - 899 2010.07

Research paper (scientific journal), Joint Work, Accepted

Cooperative control of a robot team through objective achievement

FARINELLI ALESSANDRO, FUJII HIKARI, TOMOYASU NANASE, TAKAHASHI MASAKI, D'ANGELO ANTONIO, PAGELLO ENRICO

Journal of Robotics and Autonomous Systems (IEEE) 58 ( 7 ) 910 - 920 2010.07

Research paper (scientific journal), Joint Work, Accepted

自己と群の総合的評価を用いた自律移動ロボット群の協調制御手法

藤井飛光, 加藤真之, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 76 ( 767 ) 1743 - 1752 2010.07

Research paper (scientific journal), Joint Work, Accepted

乗員のダイナミクスを考慮した減衰力のリサージュ波形に着目した自動車用セミアクティブサスペンションの制御系設計

鈴木卓馬，髙橋正樹

日本機械学会論文集C編 (日本機械学会) 76 ( 765 ) 1139 - 1147 2010.05

Research paper (scientific journal), Joint Work, Accepted

平らな足と足首ばねを有する平面受動二足歩行の運動解析と歩行実験

成川輝真, 横山和人, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 76 ( 765 ) 1380 - 1385 2010.05

Research paper (scientific journal), Joint Work, Accepted

乗員のダイナミクスを考慮した自動車用アクティブサスペンションの制御系設計

鈴木卓馬, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 76 ( 762 ) 380 - 387 2010.02

Research paper (scientific journal), Joint Work, Accepted

可変剛性スタビライザを有する自動車用セミアクティブサスペンションシステムの統合制御

小瀬村領司, 鈴木卓馬, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 75 ( 761 ) 84 - 92 2010.01

Research paper (scientific journal), Joint Work, Accepted

地震の震源域と揺れの大きさを考慮したシステムの応答評価に基づくセミアクティブ免震

福喜多輝, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 75 ( 759 ) 2917 - 2925 2009.11

Research paper (scientific journal), Joint Work, Accepted

自律全方位牽引式搬送ロボットの開発

鈴木崇文, 髙橋正樹, 吉田和夫

日本ロボット学会誌 (日本ロボット学会) 27 ( 8 ) 949 - 949 2009.10

Research paper (scientific journal), Joint Work, Accepted

無人航空機における耐故障性を考慮した知的飛行制御システムの設計

小林雄太, 髙橋正樹

日本機械学会論文集C編 (日本機械学会) 75 ( 756 ) 207-216 2009.08

Research paper (conference, symposium, etc.), Joint Work, Accepted

Design and Stability Analysis of a 3D Rimless Wheel with Flat Feet and Ankle Springs

NARUKAWA TERUMASA, TAKAHASHI MASAKI, YOSHIDA KAZUO

Journal of System Design and Dynamics (JSME) 3 ( 3 ) 258 - 269 2009.07

Research paper (scientific journal), Joint Work, Accepted

システムの応答評価に基づく減衰係数切り替え型ダンパを用いたセミアクティブ免震

FUKUKITA AKIRA, TAKAHASHI MASAKI, YOSHIDA KAZUO

日本機械学会論文集C編 (日本機械学会) 75 ( 752 ) 865 - 873 2009.04

Research paper (scientific journal), Joint Work, Accepted

Design and Construction of a Simple 3D Straight-Legged Passive Walker with Flat Feet and Ankle Springs

NARUKAWA TERUMASA, YOKOYAMA KAZUTO, TAKAHASHI MASAKI, YOSHIDA KAZUO

Journal of System Design and Dynamics (JSME) 3 ( 1 ) 1 - 12 2009.02

Research paper (scientific journal), Joint Work, Accepted

走行速度を考慮した自律走行自転車の軌道追従安定化走行制御

SAGUCHI TAICHI, TAKAHASHI MASAKI, YOSHIDA KAZUO

日本機械学会論文集C編 (日本機械学会) 75 ( 50 ) 397 - 403 2009.02

Research paper (scientific journal), Joint Work, Accepted

自律全方位移動ロボットのマルチ時間スケール型行動制御手法

TAKAHASHI MASAKI, TADA YOSHIMASA, SUZUKI TAKAFUMI, YOSHIDA KAZUO

日本機械学会論文集C編 (日本機械学会) 74 ( 747 ) 2690 - 2797 2008.11

Research paper (scientific journal), Joint Work, Accepted

衛星姿勢制御用コントロールモーメントジャイロの初期ジンバル角最適化ステアリング則

NANAMORI YASUYUKI, TAKAHASHI MASAKI

日本機械学会論文集C編 (日本機械学会) 74 ( 747 ) 2698 - 2704 2008.11

Research paper (scientific journal), Joint Work, Accepted

操舵による車体挙動を考慮した自動車用セミアクティブサスペンションの総合的制御系設計

TAKAHASHI MASAKI, KUMAMARU TAKASHI, YOSHIDA KAZUO

日本機械学会論文集C編 (日本機械学会) 74 ( 744 ) 2015 - 2022 2008.08

Research paper (scientific journal), Joint Work, Accepted

Numerical Simulations of Level-Ground Walking Based on Passive Walk for Planar Biped Robots with Torso by Hip Actuators

NARUKAWA TERUMASA, TAKAHASHI MASAKI, YOSHIDA KAZUO

Journal of System Design and Dynamics (JSME) 2 ( 2 ) 463 - 474 2008.05

Research paper (scientific journal), Joint Work, Accepted

Intelligent Stabilization Control to An Arbitrary Equilibrium Point of Double Pendulum

TAKAHASHI MASAKI, NARUKAWA TERUMASA，YOSHIDA KAZUO

JSME Journal of System Design and Dynamics 1 ( 4 ) 2007.12

Research paper (scientific journal), Joint Work, Accepted

自律走行自転車ロボットの安定化走行制御

SAGUCHI TAICHI, YOSHIDA KAZUO, TAKAHASHI MASAKI

日本機械学会論文集C編 73 ( 731 ) 128 - 133 2007.07

Research paper (scientific journal), Joint Work, Accepted

Intelligent Control System Taking Account of Cooperativeness Using Weighting Information on System Objective

TAKAHASHI MASAKI, YOSHIDA KAZUO

Journal of Systemics, Cybernetics and Informatics 1.2 ( 4 ) 1 - 7 2004.12

Research paper (scientific journal), Joint Work, Accepted

Intelligent Control System Taking Account of System Evaluation Using Weighted Observational and Explicit Information

TAKAHASHI MASAKI, HATANO KEIYO, HATANO NAOKO, YOSHIDA KAZUO

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS 70 ( 692 ) 1085 - 1092 2004.04

Research paper (scientific journal), Joint Work, Accepted, ISSN 0387-5024

Intelligent Stabilization Control to Arbitrary Equilibrium Point of Double Inverted Pendulum

TAKAHASHI MASAKI, NARUKAWA TERUMASA, YOSHIDA KAZUO

Transactions of The Japan Society of Mechanical Engineers 70 ( 689 ) 15 - 22 2004.01

Research paper (scientific journal), Joint Work, Accepted, ISSN 0387-5024

Robustness and Fault-Tolerance of Cubic Neural Network Intelligent Control Method (Comparison with Sliding Mode Control)

TAKAHASHI MASAKI, NARUKAWA TERUMASA, YOSHIDA KAZUO

Transactions of The Japan Society of Mechanical Engineers 69 ( 682 ) 1579 - 1586 2003.06

Research paper (scientific journal), Joint Work, Accepted, ISSN 0387-5024

Intelligent Control Using Cubic Neural Network for Swinging up and Stabilizing Double Pendulum

TAKAHASHI MASAKI, KAZUO YOSHIDA

Transactions of The Japan Society of Mechanical Engineers 68 ( 676 ) 3636 - 3643 2002.12

Research paper (scientific journal), Joint Work, Accepted, ISSN 0387-5024

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