研究者詳細 - 村上　俊之

論文 - 村上　俊之

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Real-time foot clearance and environment estimation based on foot-mounted wearable sensors

Ishikawa T., Murakami T.

Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society （Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society） 5475 - 5480 2018年12月

ISSN 9781509066841

© 2018 IEEE. The ambulatory gait monitoring systems (AGMS) using wearable devices have a great attention for health monitoring of individuals. Foot clearance is one of gait parameters and an indicator of gait quality and safety. Conventionally, foot clearance is calculated by post-processing using several methods such as extended Kalman filter (EKF), a weighted Fourier linear combiner (WFLC), a simple biomechanical foot model, zero velocity update (ZVU), and optimally filtered direct and reverse integration (OFDRI). However, real-time foot clearance (FC) estimation is required to apply to control of neural prostheses and assistive devices to prevent falling down. In addition, since humans adapt to several environments during gait motion, walking patterns are different among leveled walk, ramp walk, and stair walk. Therefore, environmental recognition also has an important role for the devices. Aim of this study is an implication of a system which performs real-time foot clearance and environment estimation in several situations. Different configurations of infrared (IR) distance sensors are utilized with a foot-mounted inertia measurement unit (IMU: an acceleration sensor, a gyro sensor, a magnetometer, and an air pressure sensor) sensor. Two IR sensors are attached to both sides of a shoe with different orientation. Developed system is tested in case of leveled walk, ramp walk, and stair walk. As the result, the developed system can estimate foot clearance and find characteristics of walking in different gait motion.

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Position and torque sensorless motion transmission using parameter identification based on least mean squares method

Akutsu S., Nozaki T., Murakami T.

ISSN 9781509066841

© 2018 IEEE. Motion transmission is a technology which is expected to be used for teleoperation systems. Sensorless control can improve fault tolerance of teleoperation robots exposed to harsh environments. However, sensorless control methods are generally sensitive to parameter errors of an actuator. A previously proposed sensorless motion transmission method especially requires the accurate value of resistance. Therefore, this work aims to identify resistance of two direct current motors used as a master slave system. Taking account of the master slave system of which common mode and differential mode correspond respectively to torque transmission and velocity synchronization, a least mean squares method jointly using a voltage injection is newly applied to the differential mode. Simulation results validated the proposed identification method and indicated that the sensorless motion transmission succeeded using the identified resistance value. The proposed novel method will improve the usefulness of sensorless motion transmission by adaptability to parameter errors.

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Multilevel inverter topology for switching loss reduction

Sugimoto T., Nozaki T., Murakami T.

ISSN 9781509066841

© 2018 IEEE. In motor drive application, a high switching frequency is required in order to mitigate current harmonics which cause a copper loss. However, the high switching frequency makes the switching loss large. Hence, some switching loss reduction techniques have been studied before. However, they requires complicated circuits. This paper proposes a multilevel inverter topology for a switching loss reduction. By changing current paths, the proposed inverter realizes the zero current switching. It was experimentally verified that the proposed inverter realizes the zero current switching by a foundation circuit.

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An estimation method of end-point impedance based on bilateral control system

Okano T., Ohnishi K., Murakami T.

Advanced Robotics （Advanced Robotics） 32 （ 21 ） 1151 - 1167 2018年11月

ISSN 01691864

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group and The Robotics Society of Japan. This paper aims at developing an estimation method of end-point impedance. Human operators are constantly changing their end-point impedance for adapting to the surrounded environment and executing some complicated tasks, and it is highly meaningful to investigate these variations for the further understanding of human motion. Most of the conventional researches, however, have considered non-contact-point impedance or tasks that is only holding the vibrated sticks due to the experimental constraints. This paper proposes the estimation method of end-point impedance by using bilateral control system. The extra signal is added to the force controller for the impedance estimation. In addition, the effect of the bilateral controller is estimated and removed from the impedance estimation process for securing the applicability of moving tasks. The proposed method was validated through simulations and an experiment. The experimental result showed that the end-point stiffness can be estimated properly even if the operator robot was moving and changed its end-point impedance.

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Fall Prevention and Vibration Suppression of Wheelchair Using Rider Motion State

Takahashi I., Murakami T.

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 （2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018） 575 - 582 2018年10月

ISSN 9784886864055

© 2018 IEEJ Industry Application Society. In recent years, with the declining birthrate and the aging of the population, the demand for nursing care support equipment is increasing. Among them, wheelchairs are already common as nursing care support equipment. Therefore, demand for wheelchair research is high, and electric wheelchair is required to have higher functionality. In this paper, prevention of falling of the wheelchair as a part of enhancing the functionality of the electric wheelchair is described. Several studies on prevention of rollover of electric wheelchairs have already been reported, but since rider motion state is not taken into account in the calculation of rollover conditions, there is a problem that the rollover conditions does not conform to the actual situation. Therefore, the purpose of this study is to estimate the state of the rider by IMU sensor and to calculate accurate rollover condition. Several simulation results are shown to confirm the proposed approach.

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An Approach to Energy Harvesting Considering Passive Action during Walking

Kamiyama K., Murakami T.

Proceedings - 2018 12th France-Japan and 10th Europe-Asia Congress on Mechatronics, Mecatronics 2018 （Proceedings - 2018 12th France-Japan and 10th Europe-Asia Congress on Mechatronics, Mecatronics 2018） 277 - 282 2018年10月

ISSN 9781538629826

© 2018 IEEE. Along with a development of the industry, wearable devices are spreading. These devices often have a problem of a battery exhaustion. Biomechanical energy harvesting is one of the methods to solve this problem. As methods of biomechanical energy harvesting, the shoes which attached piezoelectric elements and the system which attached a generator to the knee were researched.This paper focuses on the surplus energy when walking down a slope. In order to determine the amout of the surplus energy, a passive walking model is utilized. Additionally, a method to recover surplus energy while maintaining walking stability is introduced. Finally, PI control of the boost chopper is utilized to adjust a braking torque and the amount of the generation. The validity of the proposed method is confirmed by simulation.

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Motion Control Considering Fusion of Mechanical and Virtual Impedance in Mobile Robot Systems

Sekiya K., Murakami T.

ISSN 9781538629826

© 2018 IEEE. In recent years, the applications of robots have diversified, and interest in application to human living environment has increased. To co-exist with robots,it is necessary to ensure safety against collision. Conventional collision detection with a force sensor and collision mitigation by impedance control only have low adaptability. In thispaper, collision mitigation by combination of flexible structure and impedance control is proposed. Collision detection is performed by Load Disturbance OBserver (LDOB). In addition, switching control of the collision mitigation and damper control based on the estimated disturbance torque according to the environmental situation is proposed. Simulations are conducted forverifying the proposed approach.

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Bandwidth improvement of Disturbance Observer with Low Pass Derivative FIR Filter

Hazaz M., Murakami T.

Proceedings - IEEE 16th International Conference on Industrial Informatics, INDIN 2018 （Proceedings - IEEE 16th International Conference on Industrial Informatics, INDIN 2018） 921 - 926 2018年09月

ISSN 9781538648292

© 2018 IEEE. Disturbance observer based compensation is a popular technique in motion control to compensate for the difference between an actual plant and its nominal model. Conventional implementation with pseudo derivative performs poorly when the measurement noise is large and the bandwidth has to be decreased. Low pass derivative FIR filters provide a frequency response closer to the ideal response than comparable pseudo derivative filters. This paper proposes a disturbance observer with low pass derivative FIR filter for DC motor with position measurement. The proposal is validated with numerical simulations.

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Scaling Adjustment Method for Motion Copying System with Environmental Variations

Okano T., Ishikawa T., Murakami T.

ISSN 9781538648292

© 2018 IEEE. Machine automation is getting significant attention from the society due to the declining labor population in Japan. This paper considers Motion Copying System (MCS) that is known as the machine automation method. MCS is able to play back the saved motion if environmental conditions between the saving and loading phases are the same. The variation of environmental condition, however, degrades the motion reproduction performance because the tactile information needs the bilateral communication between the master and the slave, which can also be said of the sender and the receiver, unlike the visual or audio information. This paper proposes the scaling adjustment method for compensating the environmental impedance variation between the saving and loading phases. The effectiveness of the proposal was verified through simulation.

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Robust Control Strategy for AUV with Workspace Observer

Kawamura A., Okano T., Murakami T.

ISSN 9781538648292

© 2018 IEEE. Technologies for machine automation are strongly demanded in some developed countries due to achieve various tasks which could not be treated by human. Autonomous Underwater Vehicles (AUVs) are currently being utilized for scientific, commercial and military applications. These vehicles require autonomous guidance and control systems in order to perform underwater tasks. Modeling, system identification and control strategy of these vehicles are still major areas of research and development. Various disturbance effects perturb a vehicle in underwater, but it is not really discussed by conventional control strategy. And thus this paper proposes a new control strategy which is still effective under the circumstances when the disturbance exists. Simulations were conducted for supporting the argument.

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Comparative study of soft motion for motion copying system with environmental variations

Okano T., Oboe R., Ohnishi K., Murakami T.

IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM （IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM） 2018-July 646 - 651 2018年08月

ISSN 9781538618547

© 2018 IEEE. Technologies for the skill succession and machine automation are strongly demanded in some developed countries under the circumstance of declining working population due to the lower birth rate and the aged society. Motion copying system (MCS) is one of the methods for the skill succession and machine automation. MCS is able to play back the saved motion in the case that the environmental conditions between the saving and the loading phases are the same. Conventionally, the pure position controller, the pure force controller, or Hybrid Position and Force Control (HPFC) is applied to MCS. The reproduction performance is, however, degraded when the environmental variations happen. In such case, impedance control is applicable to MCS instead of HPFC. The purpose of this paper is to conduct the comparative study of some control strategies: position control, force control, HPFC, the Position-Based Impedance Control (PBIC), and the Force-Based Impedance Control (FBIC), and clarify which control strategy is appropriate for the tasks. Simulations were conducted for supporting the argument.

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Compensation Method for Environmental Variations of Motion Reproduction System Based on the Different Control Impedance

Okano T., Ohnishi K., Murakami T.

IEEE International Symposium on Industrial Electronics （IEEE International Symposium on Industrial Electronics） 2018-June 1045 - 1050 2018年08月

ISSN 9781538637050

© 2018 IEEE. Some developed countries will encounter the shortage of working population, and machine automation is considered as one of the promising methods to overcome its issue. This paper considers Motion Reproduction System (MRS) as a method of the machine automation. MRS can be easily repeated the executed motion; however, this system is sensitive to environmental variations. One of simple countermeasures is introducing compensation values that are designed based on the environmental variations, but these values contain errors and degrade the motion reproduction. This paper proposes the modification of control impedance on the basis of the type of environmental variations, and the trustworthy information is much more weighted. The effectiveness of the proposal is verified through simulation and experiments.

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Evaluation of Gait Phase Detection Methods for Walking Assist Robot

Tawaki Y., Okano T., Murakami T., Ohnishi K.

IEEE International Symposium on Industrial Electronics （IEEE International Symposium on Industrial Electronics） 2018-June 1051 - 1056 2018年08月

ISSN 9781538637050

© 2018 IEEE. Lower paralysis interrupts the mobility and depresses quality of life. Some incomplete paraplegia have an ability to walk in rehabilitation. However, incomplete paraplegia consumes larger energy for the gait motion than able-bodied people. Therefore, it is difficult for them to walk a long time. To solve this problem, many walking assist exoskeletons have been developed. In the case of walking assist, assist timing is one of the essential factors. The mismatch of assist timing interferes user's motion, thus it is required to adjust the assist timing. To control the assist timing, gait phase detection methods are used. Gait motion is divided into several phases. Many researchers introduce the gait phase detection method to control the assist timing. However, there is a mismatch between assist torque and ideal torque which is required by the user. There are no researches to evaluate the gait phase detection methods based on the analysis of the transition of assist torque required by the user. The purposes of this research are to propose the novel FSBM and evaluate the gait phase detection methods. In the experiment, a subject walks on the treadmill with wearing knee exoskeleton. The motor of the exoskeleton is controlled by the bilateral controller. Therefore, the assist torque can be adjusted to be suited to the user by manipulating master side motor. After the experiment, the assist torque and detected gait phases of proposed FSBM are compared to the conventional methods.

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An approach to power assist hand exoskeleton for patients with paralysis

Uchida H., Murakami T.

Proceedings - 2018 IEEE 15th International Workshop on Advanced Motion Control, AMC 2018 （Proceedings - 2018 IEEE 15th International Workshop on Advanced Motion Control, AMC 2018） 657 - 662 2018年06月

ISSN 9781538619469

The aim of this paper is to propose a novel robotic hand exoskeleton which can assist disabled people with grasping objects. Existing exoskeletons cannot measure force during contact motion, and this makes it difficult to achieve accurate grasp assistance. In the proposed system the exoskeletal finger is attached to the index and middle fingers, and the robotic finger is place on the palm side, which functions as a substitute of a thumb. The upper exoskeletal finger exerts assistive force on operator's fingers, and the lower robotic finger works as a force sensor by the use of Reaction Torque Observer. Thus, human grasping force is measured during grasping, and the environmental and human forces are estimated from measured torque. The proposed system realizes power assist control without using additive sensors like force sensors or EMG sensors. The effectiveness of the proposed method is demonstrated through simulation and experiment.

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Human motion analysis and its application to walking stabilization with COG and ZMP

Kim S., Hirota K., Nozaki T., Murakami T.

IEEE Transactions on Industrial Informatics （IEEE Transactions on Industrial Informatics） 14 （ 11 ） 1 - 9 2018年04月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 15513203

A stability index has been generally used in a gait system of formulaic structure. In this standardized structure, a human model has a center of gravity (COG), while a robot device has a zero moment point (ZMP) with COG as the stability standard in the walking motion. In the gait system of wearable type, the stability of human model is closely related with the robot device, in other words, the COG and ZMP are located in the limited domain of human motion and robot task. In this paper, the human and device are designed individually and the knee joint of human is unconstrained from the device work to allow the human reliance. The stability index that includes the COG and ZMP is defined. The validation of this index is guaranteed through a few tests to describe a correlation between the stability index and the human model condition. Based on the validity of the stability index, the experiment for the walking stabilization is implemented with the ZMP estimation by reaction torque observer.

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Translation and Inclination Control for Intelligent Tension Pole Based Mode Decoupling Method

R. Hanaoka, T. Nozaki, and T. Murakami

IEEJ Journal of Industry Applications 7 （ 2 ） 158-165 2018年03月

研究論文（学術雑誌）, 共著, 査読有り

Position and torque sensorless motion transmission using voltage compensation

Akutsu S., Nozaki T., Sekiguchi H., Murakami T.

IEEJ Journal of Industry Applications （IEEJ Journal of Industry Applications） 7 （ 2 ） 150-157 - 157 2018年03月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 21871094

© 2018 The Institute of Electrical Engineers of Japan. This paper aims to realize position and torque sensorless motion transmission between a generator and a motor. The proposed voltage compensation method requires only one current sensor on the generator side. Since the motor side is completely sensorless, this system is suitable for operation under harsh environments. Comparative analyses indicate that the proposed method satisfies the conditions for the transmission of an actual tactile sensation. Simulations and experiments confirmed that motion transmission is realized using the proposed method.

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A novel detection procedure for mutations in the 23S rRNA gene of Mycoplasma pneumoniae with peptide nucleic acid-mediated loop-mediated isothermal amplification assay (vol 141, pg 90, 2017)

Sakai Jun, Maeda Takuya, Tarumoto Norihito, Misawa Kazuhisa, Tamura Shinsuke, Imai Kazuo, Yamaguchi Toshiyuki, Iwata Satoshi, Murakami Takashi, Maesaki Shigefumi

JOURNAL OF MICROBIOLOGICAL METHODS 144 192 - 192 2018年01月

ISSN 0167-7012

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Application of active driving assist to remotely controlled car in collision avoidance

Rouzier B., Hazaz M., Murakami T., Xu W.

IEEJ Journal of Industry Applications （IEEJ Journal of Industry Applications） 7 （ 4 ） 289 - 297 2018年

ISSN 21871094

© 2018 The Institute of Electrical Engineers of Japan. Road traffic accidents are a leading cause of avoidable deaths, especially among young persons. Because driver behavior is a major cause for these the incidents, any device able to help the driver should lower casualties. As an intermediary step between autonomous vehicles and human driven ones, active driving assistance technology can help the driver maintain a safe trajectory. Applying remote control to vehicles could also decrease the probabilities of accidents, by facilitating the reduction of the duration of the driving sessions, especially in fret transport applications, decreasing drowsiness of the driver, a factor that increases the occurrence of accidents. However, the addition of remote control conducts to a communication time delay that can be dangerous in cruising situations. This paper presents the application of an active driving assistant to compensate for the effects of the communication time delay in collision avoidance scenarios using a small-scale vehicle.

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Translation and inclination control for Intelligent Tension Pole based on mode decoupling method

Hanaoka R., Nozaki T., Murakami T.

IEEJ Journal of Industry Applications （IEEJ Journal of Industry Applications） 7 （ 2 ） 158 - 165 2018年

ISSN 21871094

© 2018 The Institute of Electrical Engineers of Japan. An aging society is a serious problem in many developed countries. Due to this issue, there has been a significant increase in the demand for assist devices that can support human motion. This paper proposes a novel assist device, Intelligent Tension Pole (ITP), to assist in indoor activities of daily living (ADL), and it is expected to provide support for achieving self-reliance, space saving, and stability. The structure and control system of this assist device are presented. This novel assist device is based on a movable handrail, and therefore wheels are added to the lower and upper ends of the tension pole. In addition, a ball screw, which enables the ITP to move while stretching to the floor and ceiling at any time using force control, is added. In order to improve user comfort and reduce the risk of falling down of the ITP, translation and inclination controls of the ITP are applied to the wheel control. These controls are controlled independently by the mode decoupling method. Experiments are conducted to verify the effectiveness of the proposed device and its control system.

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