Papers - NOZAKI, Takahiro

Automatic Explosives Loading System Based on Motion Reproduction Adapting to Changes in Unevenness and Hole Orientation

M Horikoshi, I Kotani, K Yane, A Watanabe, T Nozaki

IEEJ Journal of Industry Applications, 24005263 14 ( 2 ) 196 - 204 2024

ISSN  21871094

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Automation of loading explosives in mountain tunnel excavation is being promoted to solve the shortage of skilled technicians and the high incidence of industrial accidents. Loading explosives requires human-specific skills such as appropriate force, sensation, and adaptation to environmental changes, which have not been considered in previous studies. In this study, force-aware automation was realized that can adapt to environmental changes based on motion reproduction. Motion reproduction uses bilateral control to record and reproduce movements, and has the advantage of reproducing forces and teaching human skills to manipulators. Meanwhile, if the 3D relative position of a loading hole and a 6-DOF manipulator or the orientation or the unevenness of the loading hole changes from the recording mode, the recorded task will not be successful. Therefore, a method is proposed herein for detecting the 3D relative position, orientation, and unevenness of a loading hole, besides a method of motion reproduction with compensation for these changes to realize an automatic explosives loading system. The orientation is detected from the area of the ellipse extracted via image processing. Experiments confirmed that changes from the recording mode could be compensated for during reproducing so that recorded insertion motion could be successfully reproduced, even if the position and orientation changed.

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Motion Generation in Hybrid Control Converted from Human Motion Data

K Yane, T Nozaki

2024 IEEE 18th International Conference on Advanced Motion Control (AMC), 1-6  2024

Modeling of Device Using Corona Discharge Considering Voltage Range Limitation and Delay

S Yashita, H Katagiri, T Kitamura, T Nozaki

2024 IEEE 18th International Conference on Advanced Motion Control (AMC), 1-6  2024

Data generation device and data generation system

Y Saito, K Ohnishi, T Nozaki

US Patent 12,123,796  2024

Verification of Anode Position and Generated Force Vector of EHD at Wire-cylinder Electrode

T Kitamura, H Katagiri, S Yashita, Y Saito, H Asai, K Ohnishi, T Nozaki

2023 IEEE 32nd International Symposium on Industrial Electronics (ISIE), 1-6 2023-June 2023

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Electrohydrodynamics (EHD) is a thrust force produced when high voltage is applied to two electrodes, and actuators using EHD are expected to reduce equipment size and the effects of friction. However, the EHD effect of multiple anode electrodes has yet to be verified and should be considered when fabricating a multi-degree-of-freedom actuator using EHD. This paper examines the relationship between the applied voltage and the generated EHD to verify the effect of multiple anode electrodes on the EHD. Experiments were conducted using a device with two anode electrodes at right angles and another with two parallel electrodes. The results showed that the two anode electrodes placed at right angles interfered with each other, and the generated forces were not superposed. The direction of the generated force was approximately 45 deg. When the electrodes were placed horizontally, it was confirmed that the generated forces were superposed, indicating that the arrangement, not the number of anode electrodes, was the cause of the interference.

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Preliminary Study of Object Recognition by Converting Physical Responses to Images in Two Dimensions

K Yane, T Nozaki

2023 IEEE International Conference on Mechatronics (ICM), 1-6  2023

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The use of robots is desired as a replacement for human labor. However, it is difficult for robots to respond flexibly to changes in objects and environments and perform tasks. Recently, many systems have been proposed that can flexibly respond to changes by generating robot motions using machine learning. Many machine learning methods use a camera to acquire environmental information, and feature extraction is performed using images acquired from the camera using CNN (Convolutional Neural Network), CAE (Convolutional Auto Encoder), or other methods. Many methods estimate the input values in the next step by inputting the image features, position data and reaction force data acquired from the robot together into the RNN (Recurrent Neural Network), etc. However, in most cases, the relationship between the image and robot data is learned without explicitly stating it. Therefore, in this paper, the data acquired from the robot is converted to images and used in combination with images from the camera to make the interaction between the robot and the environment explicit and to improve the estimation accuracy of NNs. In simulations, the proposed method was used to perform the task of discriminating the target of motion, and the high estimation accuracy was confirmed. In the future, we plan to use this method as input data for motion generation to generate motion according to the object.

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Estimation of Coil Position Using Receiving Voltage for Wireless Power Transfer with Magnetic Field Resonance

Y Tomioka, T Nozaki

IECON 2023-49th Annual Conference of the IEEE Industrial Electronics Society …  2023

ISSN  21624704

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Wireless power transfer (WPT) is a widely used technology today, and one challenge is to prevent the reduction of efficiency due to misalignment between the receiver and the transmitter. One solution is to reduce the misalignment by positioning the receiver at the position that maximizes efficiency, but this requires estimating the positional relationship between the devices. This paper aims to estimate the distance between coils by the receiving voltage value using a magnetic field resonance-type WPT device based on the modelings of mutual inductance from previous studies. Modeling of mutual inductance is performed for the coaxial and non-coaxial coil cases, and a theory is derived for estimating the coil positions from the received voltages. Accuracy is evaluated by comparing experimental data of receiving voltage and distance between coils with theoretical values.

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Effect of Electrode's Shape and Application Voltage on Thrust Generated by Corona Discharge

H Katagiri, S Yashita, T Kitamura, Y Inada, Y Kazoe, T Nozaki

IECON 2023-49th Annual Conference of the IEEE Industrial Electronics Society …  2023

ISSN  21624704

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A method to generate wind based on electrohy-drodynamics (EHD) using corona discharge has been applied to various thrust-producing devices. However, the relationship between electrode structure and wind-induced thrust is still unclear, and electrode design guidelines have not yet been established. Therefore, this paper aims to formulate the relationship between the thrust and electrodes' configuration by taking continuous data from experiments. Experiments were conducted to investigate the change in thrust when the gap between electrodes was varied continuously, and when changing the shape of electrodes, after a preliminary experiment on the relationship between voltage polarity and thrust. Experiments revealed that thrust increased as the gap decreased at the same voltage, thrust began to be generated at a lower voltage when the emitter electrode was needles than when it was a wire. From these experimental results, it was demonstrated that the thrust was expressed as a linear equation of voltage, that there is an inverse proportion-like relationship between the gap and thrust, and that the corona discharge inception voltage became lower when needles were used as the emitter electrode, where the voltage applied, instead of a wire. These findings and considerations will greatly help to establish guidelines for designing devices using this method, which generates thrust without any moving parts.

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Development of Optical Proximity/Biaxial Force Sensor and Application to Contact Movement

T Baba, T Murakami, HI Krebs, T Nozaki

2023 IEEE 32nd International Symposium on Industrial Electronics (ISIE), 1-6 2023-June 2023

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Proximity sensors measure the distance to an object and detect contact. Hence, proximity sensors are typically mounted and used in end-effectors. There might be situations where it is necessary to acquire information on not only distance and contact; but also the normal force and shear force. The conventional proximity/biaxial force sensor utilizes beam deflection but brittle material and interference limit its performance. Here we present a novel proximity/decoupled biaxial force sensor made of sturdy materials, springs, and photo reflectors. We demonstrate this sensor's performance and advantage of the proposed sensor in teleoperation and during a task requiring rubbing an object.

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Development of Optical Distance, Normal Force, Shear Force Sensor

T Baba, T Murakami, HI Krebs, T Nozaki

IEEJ Journal of Industry Applications 12 (5), 894-900 12 ( 5 ) 894 - 900 2023

ISSN  21871094

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Proximity and tactile sensors have been widely used to control robots. However, each of these sensors has its own shortcomings. Visual sensors have blind spots, whereas tactile sensors cannot acquire information when non-contact. To overcome these problems, this study develops an optical sensor that can measure the distance and two-axis forces using a beam structure and photo reflectors. The sensor is inexpensive owing to its simple structure. Moreover, the sensor is demonstrated to have sufficient accuracy for both the distance and force measurements at 0.2, 0.5, and 1.0 Hz. Additionally, the usefulness of the sensor is confirmed based on reduced impact control at the time of contact and force control.

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Development of Automatically Controlled Facial Osteotomy Robot using Force Information-For Safe Le Fort I Osteotomy

K Niwa, K Yane, Y Kido, T Kitamura, T Nozaki

2023 IEEE 32nd International Symposium on Industrial Electronics (ISIE), 1-6 2023-June 2023

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The development of automatically controlled medical robots (ACMR) has certain limitations. Due to their rigidity, if they are used in surgery, it would be extremely difficult to protect the patient's soft blood vessels and nerves. Hence, ACMR have not been put into practical use. The main purpose of this research is to address the limitations in order to develop the world's first ACMR that has a successful practical application within surgery. The first surgical procedure we aim to apply the ACMR to is Le Fort I osteotomy in maxillofacial surgery. While performing Le Fort I osteotomy, the robots must avoid damage to the descending palatine artery, which can cause fatal bleeding. We succeeded in automatically stopping the osteotomy immediately before the artery without the need to acquire model numerical information in advance, that is, with a model-free detection. The proposed method for auto-stopping is to identify the osteotomy reaction force obtained by the reaction force observer using the concept of the Z-score.

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Attitude control method based on differential mode voltage considering start voltage of corona discharge

S Yashita, H Katagiri, T Kitamura, K Yane, Y Inada, Y Kazoe, T Nozaki

IECON 2023-49th Annual Conference of the IEEE Industrial Electronics Society …  2023

ISSN  21624704

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A corona discharge is a kind of self-sustaining discharge that is generated by applying high voltage to asymmetric electrodes. The thrust by the corona discharge is expected as a new actuator since it has no moving parts, is quiet, and is robust. However, the relationship between the applied voltage and the thrust is highly nonlinear, which means that this problem must be solved by control. Furthermore, a control system that compensates for disturbances such as wind and modeling errors is also required. Therefore, this paper proposes a control system with a voltage range limitation that takes into account the characteristics of corona discharges and the disturbance observer to improve disturbance suppression characteristics. Two experiments were conducted to confirm the effectiveness of the proposed method. The first experiment shows that the proposed method improves the response speed by 70.0% in step response. The second experiment indicates that the proposed method enhances the response speed by 60.0% in disturbance response and suppresses angle change by 42.3%. Through experiments, it is confirmed that the proposed method succeeded in attitude control on the centimeter order and improved control performance.

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Angle Control Using Corona Discharge Considering Voltage Range Limitations

S Yashita, H Katagiri, T Kitamura, Y Inada, Y Kazoe, T Nozaki

2023 IEEE 32nd International Symposium on Industrial Electronics (ISIE), 1-6 2023-June 2023

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A corona discharge is a type of self-sustaining discharge, which is often observed between pin-to-plate electrodes under high-voltage application. Force generation using the corona discharge has no moving parts and is robust; therefore it can be used as a new actuator. However, the relationship between the input voltage and output force caused by the corona discharge is highly nonlinear, so it is essential to deal with this issue through control. In particular, it is important to consider the two types of limitations induced by the corona discharge. First, the corona discharge has a lower voltage limit at which the discharge is initiated, thus without the consideration of the corona inception voltage, the response speed deteriorates, and the overshoot increases. Second, excessive applied voltage causes spark discharge, which causes safety problems. Therefore, this paper proposes voltage reference generation and an angle control method based on differential mode voltage that considers the aforementioned voltage range limitations. Simulations confirm that the proposed method improves the response speed by 13.2% and suppresses the overshoot by 28.0% when torque disturbances are added while the applied voltage fit within the desired range.

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Admittance separation method for admittance-based bilateral control

I Kotani, T Nozaki

IECON 2023-49th Annual Conference of the IEEE Industrial Electronics Society …  2023

ISSN  21624704

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Admittance-based bilateral control is reported to have the same performance as 4ch bilateral control with only force communication. However, admittance-based bilateral control was easy to vibrate when in contact with the hard environment. Previous studies did not assume the contact vibration. Damping injection is one of the effective methods to suppress the vibration, however it generates the extra operational force proportional to velocity. Thus the operability deteriorates. To suppress the contact vibration, this paper proposed admittance separation method. This method used different admittance values for position control and acceleration feedforward. Making a smaller values of admittance for position control is effective in suppressing vibration when in contact with the environment. Moreover, the extra operational force is inertial force, so it is generated only at the beginning of the movement. Thus proposal has advantages in terms of operability. The validity of the proposal was confirmed by simulation of contact with the environment.

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Control system, control method, and storage medium

T Nozaki

US Patent App. 18/014,116  2023

Development of an optical sensor capable of measuring distance, tilt, and contact force

T Nozaki, HI Krebs

IEEE Transactions on Industrial Electronics 69 (5), 4938-4945 (IEEE Transactions on Industrial Electronics)  69 ( 5 ) 4938 - 4945 2022.05

ISSN  02780046

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Depth, proximity, and tactile sensors are often used in robotic object manipulation. The three types of sensors are combined to address each sensor limitation: Depth use is limited by blind spots and measurable range, proximity sensor is limited to millimetric distances, and the tactile sensor requires direct contact with the object. Here we present a novel sensor that can simultaneously measure millimetric distance and surface tilt, as well as contact force. We demonstrated the advantage of this novel sensor during a contact task. There, we implemented an admittance control and succeeded in achieving smooth transition from zero- to infinite-impedance contact condition and vice-versa. This novel sensor affords the realization of advanced interactions between robot and objects and contrary to previous approaches - limited by distance, blind spots, and impact force during initial contact - demonstrated good performance at all times with smooth and continuous measurements during contact.

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Work in the time of Covid-19: actuators and sensors for rehabilitation robotics

R Chaichaowarat, S Nishimura, T Nozaki, HI Krebs

IEEJ Journal of Industry Applications 11 (2), 256-265 (IEEJ Journal of Industry Applications)  11 ( 2 ) 256 - 265 2022

ISSN  21871094

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This paper reports on our work conducted during 2020 in the development of actuation and sensing techniques and devices. In gait rehabilitation, active body weight support systems are often needed to guarantee the safety of patients. These support systems are required to operate at two distinct operation points: A high-force operating mode to hold a patient and prevent falls and, conversely, a "transparent mode"that reduces the mechanical impedance of high-force actuators to enable patients, even those who are weak or paralyzed, to easily express movement. However, the ability to deliver high forces and easily manipulate robots is a key challenge in improving the force-based interaction control. Force feedback is an effective approach to reduce the inertia and friction of robots, but stability is paramount particularly when interacting with humans. By modeling the environment as a second-order spring-mass-damper system and considering the phase response, we derived the control parameter gains required to guarantee a stable human-robot interaction. The design of actuators with intrinsically adjustable mechanical properties is a complementary strategy. For instance, the stiffness of actuators can be modulated by adjusting the unsupported length of a cantilever leaf spring. To model the spring stiffness under deflection, an ideal cantilever support model cannot be assumed for a conventional design of a slider with dual roller pairs, particularly with a soft spring. We proposed a beam deflection model considering the non-zero slopes at the contact points between the rollers and spring. The spring parameters were determined to attain the desired range of stiffness with a short traveling distance of the adjuster. For a single degree-offreedom (DOF) linear motion, we investigated a macro-mini actuation concept using an electrorheological-fluid brake. Balancing these conflicting requirements between the driving force generated from the non-backdrivable high-force unit and the low-inertia and low-friction unit was achieved by controlling the electrical field affecting the fluid yield stress between the rotor and stator electrodes of the brake. One of the limitations of the feedback control scheme was noisy force sensors. We discuss our novel proximity and force sensor using optical techniques and conclude with a description of low-profile 3-DOF flat motor.

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Recognition of environmental impedance configuration by neural network using time-series contact state response

K Yane, T Nozaki

2022 IEEE 17th International Conference on Advanced Motion Control (AMC …    426 - 431 2022

ISSN  1943-6572

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Performance improvement of bilateral teleoperation with hydraulic actuator by friction compensation

Y Saito, H Asai, T Kitamura, W Iida, T Nozaki, K Ohnishi

2022 IEEE 17th International Conference on Advanced Motion Control (AMC …    250 - 255 2022

ISSN  1943-6572

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Object Detection in Motion Reproduction System with Segmentation Algorithm

X Sun, T Nozaki, K Ohnishi, T Murakami

2022 IEEE 17th International Conference on Advanced Motion Control (AMC), 42-47    42 - 47 2022

ISSN  1943-6572

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