This paper presents a hybrid position/force control with equivalent mass matrices for position-and-force-sensorless manipulators and the evaluation of the control system. Position and force estimation methods in the controller are cascaded to estimate the position and force according to the respective characteristics of the electrical and mechanical systems. The proposed controller is designed to reduce vibration of the force control axes' motion from the cross-coupling factors of the dq-axis inductance, which cause position estimation error, and the cross-coupling effects among control axes from equivalent mass matrices, which expresses the relationship between the workspace force and acceleration. The position estimation based on the voltage equation, including the cross-coupling factors, derives compensation terms of the estimation error. The cross-coupling effects between position and force control axes in the equivalent mass matrices are designed to suppress the undesired force response vibrations. The experimental results show that the proposed system kept contact with an object during the rubbing motion by a 4-degree-of-freedom manipulator without position and force sensors. The utilized equivalent mass matrix reduced the force vibration caused by the vibration of the position estimation.

This paper aims to verify the detection accuracy of Zero Moment Point (ZMP) measurements of the human body using the Kinect sensor. In this paper, ZMP is measured based on a multi-link model of the human body. ZMP calculation algorithms using a Low Pass Filter (LPF) and Savitzky-Golay (SG) filter were constructed to investigate filtering methods that can measure ZMP with high accuracy and small lag. The accuracy and responsiveness of these filters were evaluated through experiments measuring ZMP during human walking. Experimental results show that the detection error in ZMP is dominated by the differential noise in the acceleration calculation, and applying the filter only to measured acceleration values increases responsiveness with the same accuracy as when applied to ZMP. We also found that the SG filter is superior to LPF in noise suppression and responsiveness of ZMP measurements, though it occurs overshoot in measurements.

Evaluation of the falling risk is significant for older people not to fall and become in need of care. The static posturography test is adopted to evaluate the lack of balance ability that causes the falling. This test measures the center of pressure (COP) of humans and evaluates it by analyzing the data. There are three main analysis methods: descriptive statistics, stabilogram diffusion analysis (SDA), and mathematical modeling. Descriptive statistics and SDA represent only statistical values without the mechanism of the posture control system. However, mathematical modeling evaluates the system from the model coefficients containing physical meanings, and we focus on it. The stochastic differential equation of stiffness, viscosity, and stochastic terms are introduced to the mathematical model for the static posturography test. The COP trajectory reproducibility of the model is evaluated using SDA. SDA is a time-based analysis suitable for evaluating the dynamic posture control system. In the experiment, we compare the SDA parameters between older and younger subjects and evaluate the reproducibility of the model using the SDA parameters. As a result, we confirm that the SDA parameters can classify based on age to a certain extent, and the model has higher reproducibility than the conventional model against SDA.

With the rapid aging population, the need for standing-up assist device has grown because standing-up movement is essential for independent living. The standing-up assist controller needs to accomplish high trajectory-following without high rigidity. Therefore, "compliant force coordinate transformation control (CFCT)" is applied to the controller. This control method induces user to model trajectory effortlessly. Moreover, this paper proposes the algorithm which considers the differences of standing-up movement speed. The proposed algorithm enables the assist device to support the user regardless of the difference of movement speed. The controller is evaluated through experiments.

The aim of this study was to stabilize the posture of a two-wheeled walker in a torque saturated situation during turning. A two-wheeled walker increases the torque of one of the wheels during a turn, which may result in the torque saturation. There was a problem that the posture stability could not be maintained due to this torque saturation. Therefore, this paper proposes to generate a torque reference value in a torque saturation situation when a two-wheeled walker is turning. The simulation in the proposed method was compared with the case without considering the torque saturation. The simulation results showed that both the posture stability and the turning performance were improved. This indicates that the generation of the torque reference value considering the torque saturation is effective. And, we also propose a method to make the two-wheel walker stand still.

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.

This paper aims to lower the operational force for bilateral control under time delay while guaranteeing stability. Bilateral teleoperation system enables humans to work in remote places. However, time delay on network impairs the stability and the performance. The conventional method has trade-off problem between stability and operationality. This paper introduces the concept of equilibrium acceleration, which includes both position and force information, and proposes a method to detect vibration based on the difference of equilibrium acceleration. As a result, the algorithm can be considered simply, and it is possible to stabilize only during vibration and improve the operationality in free motion. Since this paper does not focus on frequency, but vibration, damping control works only during vibration and the operational force can be reduced compared to the conventional method. The effectiveness of the proposed method is verified by simulations and experiments.

The world population is ageing. In the aged society, grasping the body condition of the elderly is helpful to choose appropriate rehabilitation. This research focuses on the outdoor walking analysis by use of the simple foot mounted IMU system. The walking feature values are estimated by the algorithm, and they are combined with the GPS data obtained by smartphone to compare the feature values of frail elderly and healthy subject. The differences of walking feature values that are calculated by this system show the usefulness of developed system. The developed system is simple, but useful to grasp the gait features changing of the user.

There are many patients with Parkinson's disease in Japan. The one of the initial symptom is tremor, which is involuntary oscillations of the body. Medications and deep brain stimulation are utilized as treatments for the tremor. However, side effects and the invasiveness to the brain are regarded as problems. Hence, the demand for the support equipment is increasing in order to suppress the tremor from outside the body. There are tremor suppression robots attached to hands and upper limbs. In other words, most researches focus on the tremor of arms. Therefore, this paper proposes the tremor suppression robot for a finger. Since the frequency of the tremor and the human intended movement are different from each other, the tremor suppression control is based on the frequency resolution. This proposed control achieves the following the human motions. The validity of the proposed method is confirmed by the simulation and experiment.

In IMUs, three sensors, acceleration, gyroscope, and magnetic, are implemented. Data get from these sensors are used to acquire posture and position of each sensor. Theoretically, from a simple integration of an acceleration and an angular velocity, position and posture could be calculated. The IMU is applied to many fields due to its user friendly structure. Human motion detection is one of interesting applications. However, small error in the measured data are also integrated, hence position error and posture error, which is also called drift, occur. The purpose of this paper is to estimate position and posture using IMUs without human model. Two IMUs are used to estimate posture and position. For posture estimation, complementation of posture angle are done from an “angular velocity” and a “gravity acceleration”. For position estimation, complementation by relative relationship between 2 sensors has been proposed. This is the novel part of this paper. Two ways of position complementation algorithm are proposed. One method is complementation by Kalman Filter, and the other is complementation by error estimation. Error estimation is based on a theory of mode transfer between relative space and world space. The validation of proposed method is done by experiment.

This paper aims to realize the pitching vibration suppressing control for the Electrical Vehicle(EV). Over many years, the active suspension has been studied as an effective technology to suppress the vehicle vibration, however it requires additional parts and consumes the enormous electric power. This paper shows the vibration suppressing method utilizing the inertial force generated by the driving motor, and it achieves the low power consumption. Through realizing the control method considering the passengers' comfortability, Frequency-weighted Linear Quadratic Gaussian was expanded to Linear Quadratic Integrator system in this paper. To validate the effectiveness of the proposed method, the simulation has been carried out, and it was confirmed to suppress the vehicle body vibration.

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.

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.

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.

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.

Gait motion is the essential function for human being. Some diseases make it difficult for people to walk. Walking assist robot has been developed to assist gait motion for disabled people. Knee Exoskeleton is one of the walking assist robots. Knee Exoskeleton generates the assist torque for knee flexion or knee extension. The direction of the assist torque is controlled by the gait phase detection method. However, the conventional robot interferes with human intention because it generates flexion torque consistently in stance phase. In early stance phase, the user wants assist torque to support knee extension, but he wants knee flexion assist torque in late stance phase. The conventional controller does not detect late stance phase. In the previous study of the author, the novel gait phase detection algorithm is proposed to distinguish late stance phase. In this research, the novel algorithm is introduced for the proposed controller. A subject walks on the treadmill while wearing the knee exoskeleton. In the experiment, the exoskeleton is controlled by the conventional controller and the proposed controller. EMG of the popliteal muscle during gait motion is analyzed to evaluate whether the proposed controller succeeds to prevent interference with user's intention. Through the experiment, it is verified that the proposed controller succeeds to decrease the EMG of knee muscle by distinguishing early stance phase and late stance phase.

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.

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.

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.

The six papers in this special section focus on the use of advanced mechatronics in research and industrial applications. Mechatronics has evolved during the last few decades to become well recognized as a philosophy of design and an engineering discipline. It has emerged through the philosophy of concurrent design of mechanics, electronics, and computer of a system for an integrated and efficient approach to system design. Most universities nowadays offer a degree in mechatronics. This stems from the fact that as technology progresses, the traditional barriers between engineering disciplines are dimensioning. Mechatronics evolution went through many stages to reach its current advanced stage.

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.

Nowadays, decreasing birthrate and aging population become to be the serious social problem in Japan. Therefore, needs of assistive devices are more and more increasing. When people use such assistive devices, there is a risk that devices cost user excessive burden. So analysis and evaluation of motions and load of person who uses assistive devices are necessary. In this paper, a model to analyze the effect of external force applied to walking person by fall prevention robot is proposed. A way of suppressing human's lower limbs load in fall prevention assist is discussed through experiments.

Two-wheel wheelchairs have advantages over conventional four-wheel wheelchairs in terms of mobility and ability of going over steps. However, two-wheel wheelchairs are unstable system, and the body of the wheelchairs must be stabilized. In the conventional method, stabilization control was achieved, but the only stability of the body has been considered and the motion of the wheel has not been controlled. In this paper, a robust wheel-velocity control is proposed in order to improve the stability and the operability of the two-wheel wheelchair. We realize both stabilization of the body and velocity tracking of the wheels using sliding mode control with disturbance observer. The validity of the proposed method is confirmed by some experimental results.

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.

The driving of unmanned vehicle has been realized step by step by the automatic vehicle in recent years. On the other hand, it is difficult to drive the unmanned vehicle full automatically in the environment in which the information is insufficient. Therefore, people have to drive the vehicle proactively in such an environment, and the teleoperated vehicle is one solution. The defect of teleoperated vehicle is its poor operability, so assist control should be added to drive the teleoperated vehicle safely. However, there is a problem that the effectiveness of assisted control depends on the sensor accuracy. In this paper, a driver assistance system that does not depend on the sensor accuracy heavily is proposed by fusing the human input and the automatic assisted control based on potential method and virtual impedance control. Steer-by-wire is introduced into the steering wheel of the vehicle so as to realize vehicle teleoperation and assisted control. The validity of proposed method is verified by simulations.

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.

In this paper, a control method to improve the static stability of two-wheeled wheel chair is proposed. The two-wheeled wheel chair is the wheel chair without caster wheels, and moves and stabilizes with only two wheels. It has good operability and capability to go over a step. However, two-wheeled wheel chair has difficulty in statical stabilization because of the structure. In this paper, the steering system is introduced to the two-wheeled wheel chair. The effect of braking force from the higher inertia and the strain of tires are considered. A miniaturized two-wheeled wheel chair with steering motors is made to conduct experiments. The validity of proposed method is checked through experiment, and the results are evaluated by the movement distance and the change of pitch angle.

With the increase in aging population of many developed countries, the demand of walking or standing assist device has grown. This paper presents structure and control system of novel assist device, Intelligent Tension Pole (ITP), to assist walking and standing 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. Experiments are done to verify the effectiveness of the proposed structure and control system.

This paper describes a new measuring model of human body motion using 3D gyro sensors. Proposed model is applied to measure forehand swing motion of tennis players, and swing behaviors are captured. With proposed model, body motion and flow of energy between tennis players are compared. This method can be applied to various motion research with small cost.

Various driving support systems to avoid traffic accident have developed and have been put in the real world. On the other hand, only a few collision avoidance systems with the steering wheel have been put in the real world. In addition, most of these systems target avoiding other vehicle. But the number of traffic accidents concerned with a bicycle is next to it of a vehicle. So driving support system for collision avoidance of the bicycle is necessary. In this paper, steer-by-wire is introduced into the steering wheel of the vehicle and the driving support system which realizes the most suitable steerage to avoid collision with the bicycle by considering position, velocity, and inclination of running bicycle is proposed. First, the modeling of the driving support system is introduced. Second, the control system is designed which is composed of impedance control and model predictive control. Third, the driving simulation is conducted to verify the effect of the proposed method. Finally, conclusion and the future works are described.

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.

Recently, two-wheel wheelchair has gained a lot of attention because of its high mobility. It has no caster, so it must be kept stable by stabilization control. Operator must move his body back and forth in order to operate the wheelchair. Usually pitch angle command is zero in order that the seat of wheelchair keeps flatly. In this paper, the method of generating pitch angle command is proposed so that wheels accelerate smoothly. Ideal trajectory of wheel velocity is given as curving line and pitch angle command is calculated from this ideal trajectory. The validity of the proposed method is confirmed by the experimental results.

Nowadays, the world trade volume is increasing. In many countries, the demand for container cranes is very high in order to handle the boomimg trade. The object of the crane system is to load containers between ships and shore. Operators need to convey containers safely and efficiently. However, operation of the crane system requires expert skill because of its underactuated system. Information of the sway angle of the payload is needed to accomplish operators' tasks, but many sensors are used to get the sway angle information. They cost a lot. Therefore, there is demand for the crane system which requires no sensors. In this paper, an estimation method for the sway angle is proposed by using reaction force observer (RFOB) instead of sensors. In the experiments, a method to compensate static friction between the trolley and the rail is proposed because there exists static friction which prevents the trolley from moving on the rail. The efficiency of this method is verified by simulations and experiments.

Lacking in adequate care for the elders, especially those who are walking with inconvenience is becoming a growing problem for the aging society. The elders who walk with inconvenience, once they fall down, it is very dangerous. It is also necessary for the elders to exercise walking in order to keep normal social life. Many kinds of walking aids have been developed, but most of them are fail to avoid the elders' falling down problem which is an important issue for aged care. So far, there are few researches focusing on the walking cooperation between human and legged robot. The Inertial Measurement Unit (IMU) contains a triaxial (3-D) accelerometer, a triaxial gyro (angular rate sensor) and a triaxial magnetometer, and consequently in this paper, one IMU sensor fixed near the elder's waist to measure the posture is proposed in case that the elders fall down. Two short encoder links tied on human two legs can measure the rotate angles of thign and supply the command to the proposed device. To make human feel comfortable under various situation, impedance control is also employed in this system. The performance of the approach proposed in this paper has been examined by experiments.

Recently, two-wheel wheelchair gains a lot of attention since it has high mobility better than conventional four-wheel wheelchair. Two-wheel wheelchair consists of two actuated wheels and it is similar with wheel inverted pendulum. Therefore, stabilization control is utilized to sustain the human posture with safety. In this research, the motion of two-wheel wheelchair on the slope is considered. Repulsive compliance control with Reaction Torque Observer (RTOB) is conducted in order to determine the optimal pitch angle command for going up and down the slope. Furthermore, parameter determination of repulsive compliance control is analyzed and appropriate parameter for the motion on the slope can be determined. Simulation and experimental results show the validity of proposed command generation.

Master-slave system with bilateral control is expected to be a key technology for the next generation robots. Since position and force information are transmitted bilaterally, operators can operate the slave robot in a remote place, and feel a tactile sensation of the remote environment. Thus, by utilizing bilateral control, teleoperation with high operationality can be realized. On the other hand, it can be said that the accuracy of the task depends on operator skill, and the burden of the operator is quite high. The purpose of this research is to realize a system which human can modify the task conducted by the slave robot autonomously. With such system, high efficiency of the robot and human skill can be integrated, and thus the burden of the operator will be reduced. In the proposed system, when the operator doesn't operate the master robot, the slave robot conducts the task according to the position command or the force command given beforehand. If the operator operates the master robot, these commands are modified according to human operation. In this paper, 4ch based virtual impedance controller is proposed to realize a desired system. Experiment is conducted to verify the validity of the proposed method.

With the rapid increase in aging population of many developed countries, the need for robotic gait training has grown. This paper presents a novel gait rehabilitation system, where conditions for realizing “stable gait” are first defined, and then the control system is designed to be adjustable and compliant to patients of different walking abilities, while also satisfying the gait conditions. The proposed controller focuses on the reaction force of the end-effecter connected to the patient's lower legs, and coordinate transformation is used to divide the reaction force into tangential and normal components based on the command trajectory, and a virtual force-railway-like trajectory is constructed to guide the leg movements in the correct direction. A gain η is introduced in the controller to adjust the flexibility of the force-railway. Experiments are done to verify the effectiveness of the proposed controller.

The master-slave system is expected to be a key technology for the next generation of robots. Indeed, in many fields of operation, a master-slave system is needed to remotely perform tasks in unknown environments. However, in past researches, master-slave systems consisted of the ground based devices with limited workspaces. In this paper, the teleoperation system consists of a 3 DOF haptic device and a two-wheel driven mobile manipulator. In this system, the working areas of these robots are different. To realize the expansion of the working area of this system, in this paper, a master-slave control by force feedback based virtual impedance controller with scaling ratio and the algorithm extending the working area of the slave robot were proposed. In this paper, the effect of the scaling ratio in the master-slave controller is analyzed by using “Reproducibility” and “Operationality”. Furthermore, experimental results show the efficiency of the proposed method.

This paper proposes a method for tracking control of underactuated system such as two wheel mobile manipulator based on zero dynamics. This proposal makes it possible to control mobile platform position independently while stabilizing COG and servoing end-effector position, although mobile platform position depends on other control task in conventional methods. Proposed method is based on zero dynamics of the system that describes mobile platform response as the result of COG and end-effector position control. It is revealed that zero dynamics depends on only COG position if it is assumed that COG and end-effector position control is enough quickly controlled compared with mobile platform position. Therefore, proposed method generate COG command trajectory as mobile platform converges to desired position command. In order to make the system stable, COG trajectory is planned as it will converge to zero if mobile platform position converges to its command.

The paper describes a stabilization control of two wheels driven wheelchair based on pitch angle disturbance observer (PADO). PADO makes it possible to stabilize the wheelchair motion and remove casters. This brings a sophisticated mobility of wheelchair because the casters are obstacle to realize step passage motion and so on. The proposed approach based on PADO is robust against disturbance of pitch angle direction and the more functional wheelchairs is expected in the developed system. The validity of the proposed method is confirmed by simulation and experiment.

Controlling a riderless bicycle is a challenging problem because the dynamics are nonlinear. In this paper, an innovative robust control strategy based on 2ndorder sliding mode control (SMC) is proposed for the stabilization of an autonomous bicycle. In order to improve overall performance, application of a disturbance observer (DOB) is suggested. The combination of 2ndorder SMC and DOB enables to increase the robustness of the system trajectories while avoiding the chattering phenomenon. The proposed control scheme is validated by simulation and experimental results for bicycle stabilization at low and zero velocities.

This paper describes a control strategy of a proportional-integral-derivative (PID) controller based on stability analysis considering passivity in null space motion of redundant manipulator. Control spaces of redundant manipulator are divided into work space and null space. In the proposed approach, a disturbance observer is employed in work space, which is called work space observer. On the other hand, null space uses PID controller which is passive controller. Using gamma-dissipative property, the PID controller can compensate null space without deteriorating the motion stability. This means that the proposed approach makes it possible to realize stable and dexterous null space motion effectively. The validity of the proposed approach is verified by simulations and experiments of 4-link redundant manipulator.