As the world has become increasingly electrified in recent years, wireless power transfer (WPT) has been gaining attention as a novel charging method. Among various WPT methods, the magnetic resonant coupling type is used in applications such as electric vehicles (EVs). However, the magnetic resonant coupling type has the problem that only half of the magnetic flux of the coil contributes to the power supply, resulting in magnetic flux leakage. Therefore, this paper focuses on a magnet arrangement called a Halbach array, which strengthens the magnetic flux on one side and weakens the magnetic flux on the other side. This paper applies the Halbach array coils as a receiver to improve the power-transfer efficiency in WPT system. Experimental results confirm that the proposed receiver with Halbach array coils achieves higher efficiency than the conventional square coil receiver across air gaps of 10 mm to 70 mm at constant dc input power.

This paper presents a framework for intuitive teleoperation of a 1-degree-of-freedom (DOF) robotic gripper using hand gesture data, focusing on dimensionality reduction, impedance control, and reaction force prediction. High-dimensional hand kinematics are compressed into a 1-dimensional (D) latent command using a combination of Principal Component Analysis (PCA) and Autoencoder (AE) for robust mapping. The gripper operates under impedance control to perform grasping on soft objects. A Long Short-Term Memory (LSTM) network is trained to predict reaction forces using past gripper positions, user commands, and object labels, using ground-truth torque provided by a Reaction Force Observer (RFOB). The model relies only on static position data and temporal context, omitting velocity and acceleration to reduce complexity. This lightweight approach allows virtual force feedback to be generated directly from hand gestures without physical force sensors. Experiments show accurate gripper control, noise robustness, and real-time performance. The force prediction model achieves an R2score of 0.9778, and PCA-Autoencoder (PCA-AE) outperforms conventional methods in balancing variance capture and noise robustness. The framework is suitable for force-sensorless teleoperation systems and virtual environments, such as surgical training or simulation, where realistic force interaction is required without hardware feedback. Additionally, predicted forces can support safety mechanisms, such as overgripping prevention, by estimating contact forces before execution.

Bilateral teleoperation is a key technology that enables to perform contact-rich tasks remotely. Bilateral teleoperation using commercial industrial manipulators has practical advantages, however, industrial manipulators have low backdrivability and no torque control, so admittance-based force control is required. 2ch admittance-based bilateral teleoperation has been proposed that is compatible with industrial manipulators. However, the conventional 2ch admittance-based type does not take into account the discrepancy of admittance control period and communication period between the leader and the follower that bring out position drift. In this paper, 4ch admittance-based bilateral teleoperation that prevents position drift is proposed, and a comparison between three constructs of admittance-based teleoperation using position-controlled industrial manipulator is conducted through experiments using commercial industrial manipulators Yaskawa GP7 and HC10DTP.

Environmental recognition has an important role in tele-operation. It contributes to the stabilization of complex interactions of robots with the environment. Previous studies have focused on the vision-based method. However, subject dynamics, expressed as stiffness or viscosity, can not be obtained from visual information. One method to determine this is to apply a probing signal to the system and satisfy persistent excitation (PE). However, it comes with the disadvantage of deteriorating operationality for the vibration. Thus, this paper proposed a probing signal compensation method for a 4ch bilateral control system by using a band-pass filter (BPF). Therefore, dynamics identification was accomplished with sufficient PE derived from the probing signal. While on the leader device, oscillations were suppressed and operationality was guaranteed. The proposal contributes to compatible environmental recognition and operationality indemnification for tele-operation systems.

Wireless power transmission (WPT) is a major technology and is mainly used in transmitting power to small electronic devices. WPT is also expected to be used for larger, higher-power devices such as EVs. One of the problems with the use of WPT is the loss of efficiency due to the misalignment of the transmitter and receiver coils. Previous studies focus on circuital methods to prevent efficiency loss such as impedance matching or frequency tuning. However, these methods do not solve the coil misalignment itself. The purpose of this paper is to propose a two-axis position estimation method in order to eliminate the misalignment. The two axes mean the parallel and vertical directions of the coils. Knowing coil position information in two axes will contribute significantly to position adjustment between coils, compared to the case of only one axis position information. This paper also verified the accuracy of the proposed method experimentally.

Motion reproduction is a motion generation method in robotics characterized by the small amount of required data and its adaptability to environmental variations. However, completing the task is difficult when the environmental position variation is significant. Therefore, the proposed method generates motion data that is adaptive to environmental fluctuations by performing motion reproduction, with data integrating the position and velocity responses when motion reproduction is performed and the original force response. In simulations, it successfully made contact with the environment even when the distance to the environment was varied. In other words, the proposed method can create motions such that the task succeeded using the failed reproduction data.

Electroaerodynamics (EAD) is a phenomenon that generates a gas motion by applying high voltage between electrodes. One method of creating thrust with EAD is the use of the corona discharge, which is a self-sustaining discharge. Since it does not require any moving parts, the corona discharge produces thrust robustly and quietly. Therefore, this thrust system is expected to be utilized as the thrust source for drones. However, since the relationship between thrust and applied voltage is nonlinear, dealing with this problem in control is indispensable. Although some studies have been conducted on control methods with the corona discharge, few have been performed on multi-degrees of freedom (DOF) control based on theoretical modeling, which is essential for achieving attitude control during flight. Thus, this paper proposes a control system based on theoretical modeling to realize 2-DOF height and angle control. This study utilizes the idea of differential mode and voltage range limitations and introduces a disturbance observer (DOB) to construct a control system. Two simulations are conducted to verify the effectiveness of the proposal. The first simulation shows that the proposal can follow the command value with small errors, indicating the possibility of multi-DOF control. The second simulation revealed that the proposal significantly suppressed attitude change under disturbance and contributed to improved responsiveness.

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.

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.

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.

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.

Interior Permanent Magnet Synchronous Motors (IPMSM) are an important component for a robotic application because of its high torque property. In order to drive IPMSM with high efficiency, feedback control with rotor position sensors is utilized. However, since those sensors make the instrument size large and the cost high, many researches on sensorless control which is feedback control without position sensors have been conducted. Especially for low-speed range, sensorless control with the use of additional high-frequency signals to detect rotor position has been proposed although these signals might cause rotor vibration or low efficiency. This paper proposes a novel position estimation method based on disturbance observer which detect position estimation error. The estimation method achieves detection of rotor position at low speed since rotor saliency and current derivative are utilized. This method differs from conventional observer-based methods in that the disturbance observer not only estimates the phase, but also estimates the term proportional to the axial error and applies a compensation voltage for it. This method also avoids to use any additional signals such as high-frequency voltage for the estimation. The effectiveness of the proposal was confirmed by simulations.

Robotic teleoperation with a bilateral control system has attracted attention owing to its haptic transmission performance. However, conventional bilateral control systems require broadband communication to transmit the vivid haptic sensation. This problem limits the application range of the bilateral control systems. The communication traffic can be reduced by predicting and extrapolating the incoming data. However, in the conventional prediction-based methods, only one type (e.g., position, velocity, or force) of data is transmitted per one direction because of the difficulty of predicting multiple independent data. The novelty of this article is the realization of the prediction-based traffic reduction in the four-channel bilateral control system that transmits accurate haptic sensation by communicating both position and force data. By equivalently transforming this control scheme in the structure of impedance control, the transmit data are summed up to one data, equilibrium force. The equilibrium force is not only transmitted but extrapolated on the receiver side. As a result, the communication frequency becomes low without degrading haptic transmission performance. The validity of the proposed method was confirmed through experiments and succeeded to reduce the communication data size to less than 3.0%. The proposed method helps to realize a high-performance bilateral control system on band-limited networks.

This paper proposes a novel online motion modification method in motion reproduction system. Motion reproduction is used to reproduce human motion saved through bilateral control. Bilateral control is a teleoperation which can transmit both position and force. Human judgement is needed for compensating the saved motion when the environment is different. However, conventional motion reproduction system only relies on saved motion or environment in slave side. Therefore operators in master side cannot modify the motion after motion has been saved. Instead of just reproducing the motion data, the proposed method adds master system at motion reproduction phase so that an operator can modify the motion. If the master system is simply added to motion reproduction system, the operator's motion and saved motion will interfere each other. Therefore, we propose to use weightings to suppress the interference. Simulated results validates the effectiveness of the proposal.

Bilateral control can realize haptic feedback required for securing safety and diversity in teleoperation by robots. Since conventional approaches are based on a servo controller which has high-performance current control or torque control, there is a barrier for advancing into society. The objective of this paper is to propose a design method of the bilateral controller using velocity control driver to achieve haptic feedback. The velocity control driver such as an inverter is widely used in the industrial fields. In the proposed method, a reaction force observer modified for velocity control driver is used to estimate environmental reaction force. The control system is constructed by applying the concept of hybrid control which controls velocity and force independently, and the concept of modal space which separates motions into functions is also applied. Furthermore, the proposed bilateral controller is designed based on the ideal conditions of operationality and reproducibility. The validity of the proposal is verified through a simulation and an experiment. The obtained results show that the proposed controller successfully achieves the teleoperation with haptic feedback using velocity control driver.

Bilateral control is getting much attention as a key technology in teleoperation. A reproducibility is one of the performance indices of bilateral teleoperation, and four-channel acceleration-based bilateral control (4ch ABC) which has a high reproducibility with wide bandwidth enables operators to feel environmental impedance, clearly. Both position control and force control are required for the 4ch ABC, and a PD controller and a P controller are often utilized with a disturbance observer (DOB) and a reaction force observer (RFOB). This paper discusses how operators can feel environmental impedance with wide bandwidth in the 4ch ABC. A damping ratio of a PD controller has been, conventionally, set about 1 by imitating a traditional design principle of servo control. This paper theoretically reveals that a velocity feedback gain of a PD controller affects a bandwidth of reproducibility as a synergy with observer gains of a DOB, and a PD controller using a high velocity feedback gain is introduced. The validity of the theoretical analysis is confirmed by simulations and experimental results.

In robotic systems, reduction drives are utilized to increase actuators' force. Actuators with a constant reduction ratio can not achieve characteristics of both high velocity driving and high force driving. In order to perform various tasks, high force drive and high velocity drive are required for robotic actuators since required driving characteristics are different among tasks. Therefore, a mechanism which can change a reduction ratio continuously is needed. This paper proposes a mechanism that can change a reduction ratio with a linear electro-hydrostatic actuator (EHA). The proposed mechanism switches between two discrete reduction ratios by switching two oil paths with solenoid valves. Furthermore, this paper realizes a continuously variable reduction ratio by switching the solenoid valves quickly. This paper confirms that the reduction ratio changes continuously and widely by simulations.

Recently, for renewable energy applications, multilevel inverters are an attractive option due to their advantages, such as harmonics reduction, low electromagnetic interferences, and small voltage stress. Additionally, lower DC-link voltage should be converted to higher AC voltage, which needs an inverter and a DC-DC boost converter or a transformer. However, the two-stage conversion reduces efficiency and reliability in renewable energy applications. Hence, a single-stage conversion system which can directly change the lower DC-link voltage to higher AC voltage is required. Some single-stage conversion systems have been proposed before. However, the maximum boost ratio and the level of these systems are constant, which limits applications. This paper proposes a multilevel boost inverter stepping up the AC output peak voltage at any boost ratio by changing the number of switched capacitors. The operation principle and the boost ability with multiple boost ratios are confirmed by simulations.

In this paper, Disturbance OBserver (DOB) and Reaction Torque OBserver (RTOB) considering reluctance torque is proposed. By changing the structure of DOB when performing Maximum Torque Per Amplitude Control (MTPAC), a high torque and a robust control system is designed. Specifically, a control system resistant to noise is designed by considering the reluctance torque in the torque constant part. The proposed method is effective in situations where noise is large, as in position sensorless control. Due to the noise resistance, the vibration of the current or torque is reduced. Also, by considering the reluctance torque, the estimated value of the reaction torque can be estimated accurately. Therefore the performance of the force control is improved. The effectiveness of the proposed method is confirmed by simulation.

Recently, network-based control systems attract a lot of attentions. One of the applications of such control systems is haptic transmission using a bilateral control system. In order to construct the bilateral control system over the time delayed-network, many researchers have proposed many methods and succeeded to improve the stability and performance of the system. By assuring the system's passivity, some of conventional methods have succeeded to stabilize the system even when the communication blackout occurs. However, the passivity-based methods are conservative and deteriorate the performance. In this paper, the mode shifting method is proposed to deal with the communication blackout without considering the system's passivity. In the proposed method, the bilateral controller is shifted to a local controller when the communication blackout occurs. By shifting to the local controller, the system is not destabilized by the blackout. Moreover, when the communication recovers, the bilateral controller is gradually restored to regulate the robot's output power. Owing to the power regulation, the robots never damage environmental objects during and after the communication blackout. Therefore, the proposed method realizes stable and safe control even under the blackout. The validity of the proposed method is confirmed by simulations and a experiment.

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.

In this paper, a new approach for high-precise force control in repeated tasks is proposed. In the general force control, the feedback control tends to be used for a matching the output force to the desired force safely. However, when the feedback control is used, the input of the plant does not change until the error is observed. The characteristic makes reactivity bad. In the position control, the model-based feedforward control is often used to solve this problem. However, the model-based feedforward control cannot be used in force control due to the difficulty of making the accurate model. The main reason of this problem is the uncertainty of the environmental impedance. Owing to the uncertainty, the model-based feedforward control cannot work properly. To solve this problem, Iterative Learning Control (ILC) is used in this paper. ILC does not require the accurate model, and it is able to match the output force to the desired one through repeated trials. However, the convergence condition in force control has not been analyzed until now. In this paper, by taking account of the environmental impedance of the object, a new convergence restriction is proposed. Under the proposed condition, the force control in repeated tasks becomes more precise. The procedure was demonstrated on simulations.

In this paper, friction-reduced scaling bilateral control system for micro force transmission is proposed. Recently, demand for micro manipulation is drastically increasing in the fields of medical or biological science. In order to support micro manipulation, many researchers are trying to apply force feedback to the manipulation. One of the methods is bilateral control with Reaction Force Observer(RFOB). Bilateral control system is composed of a master robot and slave robot. Slave robot tracks master robot's motion and transmits reaction force to operator at master side. In the conventional bilateral control system, if reaction force is smaller than frictional force of machine structure, operator cannot distinguish the slight reaction force at hand. In this paper, actuator is supported by fiber to reduce the frictional force. Furthermore, disturbance arisen by fiber tension is modeled, and compensated. Experiments are conducted to validate the proposal.

Conventional robotics have always pursued methods to bring robots near human. Human robot interaction (HRI) has gained great momentum to realize freeing robots with various control methods to ensure their safe operations with human presence. Soft robotics, alternatively, focuses on building robots mainly made of low elastic moduli materials, which may not be capable of harming humans due to nature of the materials they are made of, nevertheless, requires stiffness augmentation to be able to transmit relatively higher forces. In this study, we designed and fabricated an underactuated soft robotic finger using fused deposition modelling type 3D printing with a thermoplastic elastomer material. Robotic finger is actuated with a tendon-cable attached to a linear servo-actuator while secondary linear servo-actuator is used to control position of a stiffness-enhancement unit made of bistable metal strips. In order to verify stiffness enhancement, we perform precise position control and estimate external disturbances. Experimental results suggest that estimated external disturbances (i.e. stiffness of soft robotic finger) change under the same position conditions (finger flexion) thanks to precise robust motion controller.

Recently, Wireless Power Transfer (WPT) via Magnetic Resonant Coupling is especially focused around the world. Since a space will have a lot of devices in the future, WPT considering multiple devices will be required. It is important to consider not only power transfer efficiency but also power distribution when power is wirelessly transferred to multiple devices. The amount of received power in a receiver depends on the impedance of the receiver and the ratio of power distribution has the relation to the impedance. Conventional WPT system requires a few controllable repeaters and the large size of the receiver. In this paper, a variable impedance circuit for power distribution is proposed. Using the proposed circuit controllable by DC voltage, the problem for the conventional system is solved. In the future when WPT is popular, the circuit realizes electrically controllable power distribution.

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.

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.

Hand recovery process is a major issue in the rehabilitation field as hands are vital to perform most daily activities. This paper presents the design and evaluation of a one actuated degree-of-freedom exoskeleton finger using flexible actuator to assist patients in rehabilitation process and more specifically in tendon recovery protocols. The control strategy based on the motion-copying system is used to be able to take advantages of the sensation of the patient. The wearability and adaptability of the device are improved, compared to other specific devices, mainly by the use of remote actuation and light-weight materials. Evaluation of the device in terms of wearability, adaptability, repeatability and accuracy of the position estimation are conducted. All these criteria are confirmed. The next step is to test the device in actual recovery protocols to evaluate its efficiency.

This paper aims to develop the method for identifying human and environmental impedances with information in the frequency domain by using bilateral control system. In the conventional method, a sinusoidal wave is added to the common mode of bilateral control system, however, this method cannot extract haptic information in frequency domain. Human impedances are assumed to change every moment, and the identification method of impedance is strongly desired to develop. In this paper, low-pass filtered M-sequence signal is added to the bilateral control system for identifying both human and environmental impedances with information in the frequency domain. Experiments were conducted for verifying the effectiveness of the proposed method.

In this paper, motion-reproduction system for picking by multiple-DoFs manipulator with a stereo camera is proposed. The conventional motion-reproduction is able to pick different sized objects because of considering force in the control system. However, the conventional system has difficulty in picking the positional changed objects in motion-reproduction. The proposed method compensates the positional fluctuation of picking objects by image processing information and reproduce saved motion successfully. The superiority of proposal is confirmed through experiments. In the experiment tomato and a toy strawberry was used for picking by multiple-DoFs manipulator. The manipulator with proposed method picked the object successfully.

This paper proposes a haptic prosthetic hand to realize intuitive operation for upper limb amputees. In the conventional myoelectric prostheses, it was hardly unable to control the grasping force precisely or to grasp an unevenly shaped object flexibly. In this paper, development of haptic prosthetic hand is achieved, which realizes intuitive operation by the following two functions: first, is the transmission of force sensation to the master interface attached to the healthy part of the body, second, is an adaptation to the shape of an object with flexibleness. The developed haptic prosthetic hand has multi degrees of freedom (DOFs), and the master interface has a limited number of DOF. Therefore, to control the multi-DOFs haptic prosthetic hand by a simple operation of the master interface, different DOF bilateral control is implemented as a control method. Haptics is used to realize intuitive operation, and the proposed variable compliance control is used for environmental adaptation. These functions enable to replace the force sensation of the missing hand, by any remaining healthy part of the body. Experiments were conducted to evaluate the function of the developed haptic prosthetic hand.

As the development of electrical transportation systems, two-wheeled mobile robots have been widely studied because of the high mobility. Among them, the two-wheeled wheel chair is the wheel chair without caster wheels, and moves and stabilizes with only two wheels. However, wheel chairs cannot move lateral direction in general, and they sometimes fall down and cause into serious accidents. In this paper, lateral directional mode and its control method are proposed to solve this problem, and the validity of proposal is checked through simulations. The results are evaluated by the movement distance and the change of body's pitch angle.

With the increase in aging population of many developed countries, the demand of walking or standing up assist device has grown. This paper presents structure and control system of novel assist device, Intelligent Tension Pole (ITP), to assist walking and standing up in room considered supporting for self-reliance, space saving, and stability. Two-wheel and one-wheel are added to lower and upper ends of tension pole collectively, and ball screw is added to move while stretching to floor and ceiling under various conditions. In addition, cooperation control of ITP with human based Ineatial Measurement Unit (IMU) to assist walking is introduced in this paper. Experiments are done to verify the effectiveness of proposed control system.

The field of human motion analysis has researched with designing the rehabilitation robot system. In the present, there are many robot systems dealing with the human motion but they are heavy and hard to use simply at home. Moreover they especially have a particular purpose focused on the single human motion then the usability of these systems is low and fragmentary about a variety of motions. To classify the various motions, we propose the approach to categorization analysis for human motion by using information of the Kinect and IMUs. It is focused on the human motion which is classified into the walking, standing up and down, and falling down motion. The two COG points of the body from the sensing results are defined as the new indexes such as distance and incline, which are the indicator to classify the human motion. To verify the verification, the theoretical human model is designed and the experiment for the various human motions is carried out by using Kinect and IMU.

Sensorless control of brushless DC motors (BLDCMs) by detecting back electromotive force (back-EMF) is widely used because of ease of equipment. As conventional method, back-EMF detecting method by using phase lock loop (PLL) is used. This method uses the nature that back-EMF of γ-axis is related to estimated angular error. As usual, back-EMF of d-axis is zero in the case of using position sensor. To compensate estimated angular error becomes zero, PLL is used. However, this method assumes that estimated angular error is very small so that PLL is not able to deal with sudden disturbance. In this paper, back-EMF detection method by using back-EMF estimation observer (BEOB) is proposed. Proposed method is able to derive not only estimated angle error but also estimated angular velocity directly. To estimate angular velocity correctly, disturbance observer (DOB) is able to be applied, and robust angular velocity control can be achieved. Then, validation under change of back-EMF constant is conducted with experiments. Back-EMF constant changes due to parameter error and environmental temperature. Therefore, comparison of PLL, method and proposed method under change of back-EMF constant is conducted. Validity of proposed method was confirmed by experiments.

This paper proposes a new state-space controller for the robust trajectory tracking control problem of multi-mass resonant systems. It is designed in state-space by combining Differential Flatness (DF) and a higher order Disturbance Observer (DOb). The former systematically generates the control input and state references of a state feed-back controller so that not only regulation but also trajectory tracking control can be performed in state-space. They are obtained in terms of differentially flat output variable in DF. The latter estimates disturbances and their successive time derivatives. Its order depends on the resonant modes of the system. The proposed controller has a two-degrees-of-freedom motion control structure. Its performance and robustness can be independently adjusted by tuning the state feed-back controller and DOb, respectively. It is designed in two steps. In the first one, the state feed-back controller is tuned by only considering the nominal plant model of the system. The nominal performance is adjusted by using pole placement; e.g., all poles of the nominal system are placed on the real axis so as to suppress the vibration at tip. The state and control input references of the state feed-back controller are obtained by using DF. In the second step, the robustness of the system is achieved by reconstructing the state vector via the estimations of disturbances and their successive time derivatives. Thanks to the proposed new state variables, mismatched disturbances are automatically cancelled by the state feed-back controller. The matched disturbances are cancelled by feeding-back their estimations through control input. Hence, the robustness of the multi-mass resonant systems is achieved. Without losing generality, the proposal is verified by considering three-mass resonant systems. Its simulation results are given to validate the proposal.

In this paper, a new robust force controller is proposed for Series Elastic Actuators (SEAs) by using conventional Sliding Mode Control (SMC) and Disturbance Observer (DOb). The position measurement of the actuator's link is subtracted from the desired deflection of the spring so that the force control goal is defined as the desired position of the motor; i.e., the force control is simply performed by designing a position controller at motor side. However, the position accuracy of the motor is influenced by the dynamics of the actuator and environment. Since they cannot be easily identified in practice, the dynamics of the actuator's link and environment are considered as unknown disturbances in the design of the proposed controller. In order to improve the robustness, conventional SMC-based robust force controller is designed without considering the unknown disturbances. Although the robust force control can be theoretically performed by using the conventional SMC-based controller, it suffers from chattering in real implementations. Conventional DOb-based robust motion controller is designed at motor side so that not only the disturbances are cancelled by feeding-back their estimations but also the control signal of SMC-based robust force controller is lowered. Hence, a simple yet efficient robust force controller is designed for SEAs. The validity of the proposed robust force controller is verified by giving experimental results.

Conventional methods for storing and reproducing task are based on only the information of the actuators in the robot. However, in these methods, reproducing the stored task is difficult when the environment differs from that in storing phase. This is because these methods consider a meaningful task as just a motion. In this paper, to reproduce a stored task even if the environment differs from that in storing phase, storage and reproduction of a task based on the controlled variable of a task is proposed. To verify the principle of this proposal, the water pouring task is considered. The proposed method can reproduce the water pouring task even if the initial weight of the water in the bottle differs from that in storing phase. The validity of the proposal is confirmed by experiments using one degree-of-freedom robots.

Screws are widely used in various types of manufactured product. For screw-tightening, the pushing force and rotary torque are required. However, usually only the rotary torque is controlled in order to control the screw-tightening process and the pushing direction is important. If the pushing force becomes small, the driver-head separates from a screw. On the other hand, if the pushing force becomes large, the friction also becomes large and increase of the pushing force is needed. Therefore, the pushing force has relationship to the rotary torque. This paper focuses on the pushing direction and the aim of the research is the fast screw-tightening. This paper shows the modified screw-tightening model. Moreover, the pushing positon is controlled based on the rotary angle to reduce the reaction force for the fast screw-tightening. The availability of proposed method is verified by the simulation and experiment.

This paper discusses visual servo system for ball dribbling by using bipedal robot "Nao". Countless papers have been written by researchers since the establishment of RoboCup in 1993, which contributes to the progress in robotics and artificial intelligent. However, only few papers discuss dribbling even though ball dribbling is one of major techniques to master to win a game. To achieve ball dribbling, rigid visual servo is needed in order to kick the ball continuously. Because of the noise caused by the oscillation of walking, it is difficult to make a visual servo system that can achieve ball dribbling. In this paper, visual servo system which is able to control both stepping control and walking pattern is proposed. The proposed visual servo system can offer more rigid visual servo with stability than the one that commonly used by applying foot step planner, walking pattern generator and image processing.

Power factor in mechanical system is a new concept to express characteristic in mechanical system. It defines dynamic behavior of the impedance characteristic in the motion. However, conventional derivation method requires short-time Fourier transformation in order to consider random input in mechanical system as a combination of sinusoidal waves. This paper proposes a novel method to obtain power factor in mechanical system. The proposed method is technically a simplified version of short-time Fourier transformation algorithm, but it does not require any Fourier transformation or complex calculations. The theory is supported by experimental comparison of the results.

Since the two-wheel electric motorcycle has good portability and flexibility, it is popular in many countries nowadays. However, keeping the motorcycles balanced, which is a valuable research in an accelerating ageing society, has not been thoroughly researched. In this paper, a novel self-balancing electric motorcycle without the handlebar is put forward to cover this deficiency. By controlling the steering, the balance of the motorcycle can be kept with its wheels swaying. And the motorcycle direction can be operated by human body. Also, three different steering phases of handleless motorcycles were discussed. The difference of these three modes were showed by preliminary experimental results.

Human motion recognition systems play an important role in improving the ability of robots to support human life. This paper proposes a novel motion recognition method based on haptic data (i.e., position and force information). First, haptic data are obtained using a bilateral control system. Second, the haptic data are divided into action components, using modal transformation. Finally, both the position and the force information in each action component are compared with recorded data. A dynamic programming pattern-matching algorithm is used to recognize the desired motion, and the validity of the proposed method is verified experimentally. In the experiments, the proposed method is applied to a grasping motion. The proposed method can trigger scaled bilateral control and assist the operator in real time.

This paper examines a stability characteristic of gyrator type bilateral control in order to determine a definite feedback gain and scaling design. Stability is examined based on root locus. Maximum stable gain, transfer impedance and transfer admittance are observed in the examination. Moreover, it is observed that at certain transfer impedance and admittance, gyrator type bilateral control and transformer type bilateral control become equivalent to each other. Validity of the analysis and characteristics of several transfer impedance and transfer admittance design are examined based on experiments.

Motion canceling bilateral control (MCBC) is a method to synchronize motion of a teleoperation robot and a target, while an operator can obtain tactile sensation of the remote target. This interface helps the operator by taking a task and reduces his/her workload. However, the delay caused by the sensors deteriorates the synchronization performance and transparency of the MCBC. Therefore, synchronization performance improving method for MCBC utilizing an extended dual sampling rate observer (EDSR observer) is proposed in this research. The target motion is modeled as a motion with constant acceleration and the EDSR observer is utilized to estimate the present position of the target. The experimental results indicated that the synchronization performance was improved by 12.2 % in maximum error ratio and 14.8 % in root mean square error ratio. The experimental results indicate an improvement of the target operationality, which suggests the clear tactile sense transmission was achieved.

Since the advance of the aging society with a falling birthrate, technical inheritance has been a serious problem. This paper proposes a method to provide a skillful motion. First, haptic data (i.e., position and force information) is acquired using a bilateral control system. Second, the acquired haptic data is divided into action components by using modal transformation. Third, position and force information in each action component are compared with recorded data concerning the skillful motion. Finally, if an operator performs motion similar to skillful motion, the recorded data is loaded to the bilateral control system. Similarity between the performed motion and the skillful motion is calculated based on dynamic programming matching algorithms. The validity of the proposed method was experimentally verified. In the experiments, the proposed method was applied for grasping motion, and the recorded skillful motion was reproduced when the operator tried to perform the skillful motion. The maximum position error was 0.072 cm.

This paper proposes a method to design bilateral control systems based on interactive parameters. Conventional design methods were based on F parameters and, mainly took care of the elements A and D in F matrix. In this research, all four elements are taken care in order to increase the degree of freedom in system design. A design is based on interactive parameters, Z1, Z2, and θI. The new design method enables an independent design of impedance transmission and scaling. The effect of the proposal is experimentally verified.

Tendon-driven rotary actuators are utilized in various robots because they are small and high output. However, if the tendon-driven rotary actuators are utilized in bilateral control system, there are two problems. The first problem is interference. Bilateral control systems with tendon-driven mechanisms require decoupling of angle tracking, torque feedback, and tension control on master side, and slave side. The second problem is elongation. The tendons are extended by applied force. Therefore, it is difficult to control the angle precisely. In this paper, a method to compensate the error caused by the tendon elongation for tendon-driven mechanisms is proposed. This compensation method is designed based on modal transformation. The validity of the proposed method is verified by an experiment. Elongation is reduced by the proposed method. In addition, angle tracking, torque feedback, and tension control on master side, and slave side are achieved independently. Experiments were conducted to confirm the validity of the proposed method. In this experiment, proposed method is applied to a bilateral control system.