This study developed path planning algorithm that mobile robot moves safety in living environment. In the human living environment, positions of objects and people change frequently. So, Robots need to move with observing environments. But, paths with traditional path planning method have concerns about collision with unobserved object when range of observation is limited. To solve this problem, we have proposed the path planning method. This method can predict change of observable area in planning and avoid robots go into unobserved area. We confirm that Robots can arrive at the destination by using our method in static field. In this paper, we developed our method in order to use the method in dynamic environment.

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This paper describes a path planning method for obstacle avoidance in local map considering obstacles existing around of the goal of the path planning and follow-up of the specified path for a mobile robot. Distance Transform method is used for the path planning considering follow-up specified path in the local map. And,ever if obstacles exist on the specified path, the goal that is suitable for avoiding the obstacles is searched by arranging candidate points for passing on the specified path.

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In this paper, we propose a method for localization accuracy improvement by reflecting evaluation of reliability of information from GPS in outdoor environment. Currently,GPS is widely used to obtain the positioning information in urban environment. However,if there are obstacles such as trees and tall buildings around the robot, signal lost and multipath is occur. Therefore, all the obtained position information is not necessarily correct. Consequently, processing each threshold with respect to the Satellites number ,positioning techniques and Carrier Noise Ratio. Additionally, to evaluate the likelihood of GPS observations by caluculating the normalized innovation square by using the motion model,we will get only the more reliable GPS observations. We show robust localization even if large error occurs in GPS observation by reflecting result of the evaluation to the localization

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In recent years, lunar and planetary explorations using planetary rovers have been increasing. The surface of the Moon or Mars are covered with loose sand and scatterd rocks. Therefore, the exploration rovers require high mobility system to traverse over rough terrain. It is obvious that vehicle parameteres, such as wheelbase, tread or the center of the gravity, significantly determine mobility performance of rovers. This paper presents an experimental analysis of the rover stability, particularly focusing on the relationship between the vehicle parameters and postural change of a wheeled rover while surmounting an obstacle on rough terrain. The stability analysis in this reseach employs a terramechanics based approach to estimate wheel sinkage, and also takes the normalized energy stability margin to indicate comparative evaluation of the vehicle parameters.

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In this paper, we propose a suspension system of two-wheel inverted pendulum mechanism that can traverse on an uneven floor. To absorb impact from a gap and improve roll stability, the two-wheel inverted pendulum is equipped with a hybrid suspension in which a spring and an actuator are serially linked. The hybrid suspension absorbs impact from the gap by spring and compensates unbalance of the upper body by the actuator. To minimize the roll angle of the upper body during going over the gap, the spring constant is optimized by mechanical simulation. We confirmed that EMIEW2 with the hybrid suspension goes over 15mm gap at 1.6m/s.

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In Tsukuba Challenge 2011, a collision occurred between two robots during preliminary running. This paper presents the technique of avoiding moving obstacles by autonomous mobile robot. First, the robot estimates the velocity vector of moving obstacles from particle filter based on laser scanner data. Next, moving obstacles are treated as if they were expanded in the direction of movement and the robot determines its rectangular space to avoid moving obstacles depending on their speed and direction. As a result, in Tsukuba Challenge 2012, safe overtaking was observed because of the avoidance of moving obstacles.

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Recent years, vibrotactile signals have been employed for realistic tactile displays. To evaluate vibrotactile signals themselves, we propose a method to compare classification abilities of these signals from machine learning. By employing support vector machine, our method evaluates about what kind of signals are suitable for classification. In this paper we discuss the difference of classification abilities between sensors, sampling frequencies, rubbing speeds, integrated signals and textures.

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We propose a combined tactile and proximity sensing device for handling robot. Tactile sensing is based on the method known as a light conductive plate. Proximity information is obtained through depth measurement from compound-eye camera stereo images. These tactile and proximity information are both captured by using the compound-eye camera TOMBO(Thin Observation Module by Bound Optics). We evaluate the performance of the sensing device and verify the availability of the device in the application to robot hand.

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Body ownership transfer in rubber hand illusion is a well known haptic illusion in the literature. In this study, we introduce the body ownership transfer into a master slave system to realize a further operability. As a preliminary test, we developed a 1 DOF rubber hand master slave system and investigated the effect of active and passive haptic interaction on the body ownership transfer.

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This paper proposes a sensing method to evaluate food textures quantitatively by physical measurement. Based on the pressure distribution during compression and breaking of a nursing-care jelly the values of sensory evaluation are estimated. For jellies whose values of sensory evaluation have been obtained, we measure the pressure distribution by using an experimental model where two gripper plates are regarded as a tongue and a palate, respectively. Based on the texture analysis for image, we extract feature values of the pressure distribution. We then derive the regression equation modeling the relationship between the feature values and the values of sensory evaluation. By giving the pressure distribution of an unknown jelly to this model, we can estimate its value of sensory evaluation. Experimental results show that values of sensory evaluation of nine kinds of jellies are accurately estimated.

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We developed a novel white cane fabricated using aramid-fiber-reinforced plastic. In this study, impact resistance of each canes were evaluated in strength test. In addition, to evaluate physical loads regarding to actual operation, electromyography of upper limb muscles are measured during touch motions with each two cane. These results show that the new cane is less than half the weight, and high impact resistance compared to a conventional cane fabricated using carbon-fiber-reinforced plastic. Moreover, muscle loads of wrist flexion muscles during touch motion can be reduced by about 20%. On the other hand, the load of the extensor carpi ulnaris muscle was increased.

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In the finger's controllers for a robot and the virtual reality, it is difficult for an operator to feel the feedback force directly because a resistance of the controllers makes the sensitivity of the fingers less sharp. Therefore, it is effective to press the fingers with lugs in order to feel the force originally. In this research, we consider the experimental conditions, lugs' diameter, height, pitch, number, position to the fingers, and tip shape, refer to former researches for making the sensitivity of the fingers better to the feedback force, and have the experiment to confirm the concept of pressing the lugs to the fingers.

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Humans control their movement based on the environmental information obtained from various sensory systems. Although it is generally known that deep sensation coordinates the control of the movement, it is assumed that cutaneous sensation also has some functions on the motor control. This means that decline of cutaneous sensation can be a possible cause of fall of walking capability. Our objective is to develop a new walking support technology using vibrotactile simulations on the lower limbs. In this paper, we developed a wearable recording and reproducing equipment of vibration propagation on legs during gait.

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Space operation type interfaces, which use gestures and hand movement in the air, provide intuitive interaction as a human interface. Haptic feedback for such interfaces will be able to enhance the operability and the reality. In this study, we propose a surface shape display method for the space operation type interfaces. We have proposed a surface shape display method by cutaneous sensation of friction through a pointing-stick-type tactile interface called 'Vib-Touch'. In this paper, we propose a new implementation of the surface shape display method to apply the space operation type interface. We evaluated the discrimination performance with the three virtual shapes in space by comparing with the real objects.

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In this paper, a concept of estimating a body's mobility and elasticity by conducting haptic sensing was proposed. A method of measuring the force applied to the body was proposed to be used in haptic sensing. In order to conduct haptic sensing a variable stiffness mechanism (VSM) using linear spring was proposed and installed in an experimental 3DOF variable stiffness manipulator. Experiments using a prototype of the VSM were conducted, and the effectiveness of the proposed VSM and the force estimation method was investigated experimentally. As a result, a modulation of the resolution of the estimated force was achieved.

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The primary purpose of using a white cane is to be able to detect street conditions and obstacles based on the reverberations and tactile information that is gathered from the tip. But users reported in interviews that used their canes to distinguish between various materials or recognize certain objects. In this study, we investigated the relationship between vibration and sense of hardness using white canes. We measured frequency of vibration of the tip of the cane by acceleration sensor when the cane contacted with rubber board that have 4 hardness levels. And using psychological experiments, we then had participants estimate their sense of hardness for each hardness level. It was found that there is a correlation between the hardness sense and frequency pattern of vibration. This result may become the basic knowledge of indirect tactile perception.

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We developed a compact load sensor using AT-cut quartz crystal resonator whose resonance frequency changes under external force, and features high sensitivity, a wide measurement range, high-speed response, and superior temperature and frequency stability. We design a quartz crystal resonator sensor to increase its sensitivity and to reduce the whole volume of the packaged sensor. We made the quartz crystal sensor and the sensitivity was increased from 574Hz/N to 896Hz/N and the volume was reduced from 423mm^3 to 226mm^3. We designed and fabricated a package of the sensor which has a mechanism of pre-loading of the quartz crystal sensor.

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This paper reports a haptic effect that feeling of friction to swipe a screen of smartphones changes depending on their thickness and weight, even if the screens are covered with the same surface materials. The reason of the effect should be related to holding position and required force to hold it. Therefore, in order to clarify the effect, we measured the force generated between the object and finger, and orientation of the finger is also observed.

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Painful thermal stimulation is known to relieve itch, which is a significant problem in many diseases. We focused on thermal grill illusion and synthetic heat, which are well-known phenomena that can generate pain or burning sensation without physical damage; we tried to achieve a similar effect via a harmless-range thermal stimulation. We developed a roller-type itch-relief device. When the device is rolled onto the user's skin, the skin is alternately exposed to hot and cold stimuli. The roller is composed of aluminum parts. One part is set to hot and the other is set to cold by embedded Peltier devices. When the device is rolled on the user's skin, the skin is alternately exposed to hot and cold stimuli. In addition, vibration is applied so that a virtual scratching feeling is presented without damage to the skin. We evaluated the device by eliciting an itch using a lactic acid solution and then applying the device. The results showed that the device provides effective temporal relief from itch and that its effect continues for a few minutes.

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With the aim of augmenting auditory sensation by tactile stimuli, we investigated cross-modal relationships between the two modalities, focusing on frequency. The results showed that frequency consonance between tactile and audio stimuli may depend on the relationship between harmonics, in manner similar to auditory waves, but with broader peaks.

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The skin-transmitted vibration might influence tactile sensations. In this paper, the skin-transmitted vibration of the finger is measured when mounting the rubber ring or attaching the non-stretching tape. In addition, pilot experiments on the sensitivity on vibration are conducted. Experimental results show a possibility of tactile sensitivity change (enhancing or desensitizing) by operating skin-transmitted vibration.

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We have developed the tactile sensor including the bidirectionality for the laparoscope-assisted surgery. In active touch, exploratory movements influences perception, but also perception influences exploration. Humans can optimize or change the exploratory movements according to the perception and/or the task, consciously or unconsciously. Our proposed sensor has a potential to use the user's ability on the haptic perception due to including the bidirectionality. A slim forceps-shaped sensor is assembled and the sensor output for a simulated lump is discussed in this paper.

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This paper proposes a new sensor for the moisture measurement on the surface of the skin. The proposed sensor measures the voltage generated by which the stainless steel film was contacted and released the skin. The moisture condition of the skin was obtained from the voltage. In the experiment, the moisture at the skin of forearm was measured by using the proposed and commercial sensors and their measured values were compared. In addition, the measurement values by the proposed and commercial sensors at two types of skin models were compared. As a result, it was shown that measurement of moisture on the surface of the skin is possible by the proposed sensor.

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In the process of developing our ultrasound-based non-contact tactile display, it is needed to check whether the ultrasound is focused as intended. It takes a lot of time to scan a microphone, feeling tactile stimulation by hand lacks spatial resolution, and other conventional visualization methods are not available in our case. This paper proposes a visualization method using viscous fluid. The viscous fluid functions as a low pass filter and eliminates undesired components such as splashes, bubbles, and traveling waves. Then it shows the spatial distribution of the DC component, i.e. acoustic radiation pressure, which is the origin of the tactile stimulation of our tactile display.

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In this paper, we illustrate a new haptic interface for a service robot. In the case of service robots dealing with humans, for safety, it is desirable for the information to be conveyed before touching. In order to achieve such function, we covered the surface of the manipulator with a large number of proximity sensor. Thereby, it becomes possible for the manipulator to detect objects before touching them. In addition, we used a small vibration motor as a means of feeding back to the pilot when the sensors react in this research. We attached vibration motors on the arm of the pilot, and vibrate the vibration motor corresponding to the sensor. Thereby, the pilot is able to know the position of the object near the manipulator, and can make the robot take avoidable maneuver before touching. Thereby, the pilot is able to know the position of the object near the manipulator, and can make the robot take evasive maneuver before touching. We confirmed the effectiveness of the system in an experimental work space.

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This paper reports the development of a tactile sensor for early detection of breast cancer. The sensor consists of a PVDF film, which is used to imitate the Pacinian corpuscles of human rapid tactile receptor and a layer of pressure-sensitive conductive rubber, which is used to imitate the Merkel's disks of human slow tactile receptor. Outputs of the two sensory materials are used in the detection of stiffness of human body tissues. The sensor was testified on a breast cancer model and the result showed that the sensor could successfully discriminate the difference in the stiffness of normal breast tissue, breast cancer tissue and tissue of fibroadenoma.

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It is well known that senses from feet greatly influence cognitive and motor functions. However we hardly know how to acquire information from such foot sense and use it. In this study, we investigated the relationship between three types of foot senses (planter pressure, vibration, and ankle motion) and cognitive functions of healthy subjects by conducting sensory evaluation tests. Experimental results show that the sense of plantar pressure significantly correlates with the cognition of shape of floor surface. In addition, it is possible to correlate with the hardness of floor.

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This article proposes a myoelectric prosthetic hand control system using a brain machine interface that uses electromyogram signals and other biosignals such electroencephalographic signals. The proposed system consists of a feature vector extractor, a neural network estimator, a reference trajectory generator, and an adaptive corrector. As a preparation, an experimental system has been prototyped without adaptive correction using other biosignals. The system is to classify 8 forearm motions by using 2 electromyogram signals and to generate reference trajectories for servo controllers of a prosthetic hand. The experimental results showed that the proposed classification algorithm has basically worked well and that the reference trajectory generator has a potential to make appropriate smooth trajectories.

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This article proposes a pedal-driven wheelchair with power assist function to allow operators with loss of muscle power to drive it. In the proposed system, the assist gain can be online changed so as to easily adjust a stress loading, and it could be helpful in rehabilitations to tune the load depending on the degree of recovery. A prototype of the proposed wheelchair has been developed and was evaluated. Experimental results showed that the power assist unit used in the wheelchair has robustly worked well against perturbations of the environment, keeping the power assist control bandwidth about 1 to 3 Hz and also that the developed wheelchair has been ready for evaluation tests.

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This article proposes a linear power assist unit for pedal-driven wheelchair and its control algorithm. The proposed power assist unit is controlled explicitly taking into consideration mechanical impedances of both a human operator and environment. In the proposed system, impedance variations for the environment are treated as a plant perturbation, but those of the human operator are considered to be identified to adapt the controller to the variations. For the first step, an identification method using Kalman filter is proposed, and evaluation results for a basic deterministic controller performance are reported. Simulation results showed that the proposed indemnification method is able to track impedance parameter varying about a frequency of 0.1 Hz. Experimental results showed that the prototype has robustly worked well against perturbations of the environment, keeping the power assist control bandwidth about 1 to 3 Hz.

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There is a growing demand for a walker for an aged person. It is a serious challenge to climb a step by the walker. A mechanism for step-climbing of the walker have been commercialized. However, a considerable amount of force is necessary to climb the step by using it. It is also expensive and has a complex mechanism. Therefore, we work on the development of a new mechanism for step-climbing of the walker. In this paper, we propose a new mechanism that focuses on a front wheel of the walker to climb a step. We verify the effectiveness of it by simulation.

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In this paper a method of Functional Electrical Stimulation using the characteristics of Interferential Current is proposed. The flexion and extension of the fingers are tested for the purpose of realizing object grasping motion. Together with flexion and extension test results, the generated forces during flexion are measured and presented.

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It is thought that burdens of the care increase by influence of decreasing birthrate and aging society in Japan. Therefore development of an "Assistive Mobile robot System (AMOS)" is pushed forward in this laboratory to reduce burdens of the caretaker. We use sensors in this study to grasp an object stably by AMOS and perform the control of robot hand. In this paper, we propose the control system for grasping an object according to the difference in hardness with the tactile sensor, and for efficient approaching before grasping with the capacitance sensor. The tactile sensor and the capacitance sensor are designed to be applied to variety of robot hand. We examined the effectiveness of these sensors. Then, we demonstrate the effectiveness of control systems with these sensors.

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We have proposed a virtual walking system with a haptic device on feet. This system consists of visual, sound, and haptic devices to present various kinds of ambient information for users. Especially, development of the haptic interface for feet soles is a new challenge. In this paper, we discuss a use of magnetic field sensitive elastomers (MSEs) as working materials for the device. First, we have discussed structure of the device using MSE. Next, we developed the haptic device unit with MSE. The performance evaluation for the unit was conducted with compression test. We confirmed that the performance of the unit was less than the target values of the frictional force. We will need to improve the device unit to achieve the target values. Therefore, we have experimentally determined the optimal thickness of MSE for the unit. And we fabricated the devices using that unit.

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In this study, we evaluated riding comfortableness of the attendant propelled wheelchair when using pressure redistributing cushions. Three types, a form type, a gel type and an air type cushions were respectively tested. The vibration propagating characteristics of these cushions were evaluated by measuring vibration of the dummy weight which was put on the pressure redistributing cushion during wheelchair running on tactile surface indicator road. In addition, a sensory test was conducted to compare the comfortableness of these cushions. Vibration wave form was analyzed by FFT, and sensory test was conducted by using questionnaire for subjects riding on the wheelchair with pressure redistributing cushion. As the result, the air type cushion indicated highest vibration damping performance, and the gel type was second, the form type cushion was third, respectively. The total result of the sensory test questionnaire correlated with the vibration damping performance. The cushion which has higher vibration damping performance provides better riding comfortableness to the occupant.

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We have proposed the fall detection method using a human pulse as a vital sign, acceleration and angular velocity. For this method, the ubiquitous pulse wave sensor that can measure a human pulse even during fall motion was developed successfully. This pulse wave sensor has the special DC-AC separation amplifier and optical modulator. Therefore, the sensor enables to solve a transient response problem and prevent disturbance by ambient light and measure a human pulse during motion. From a result of the fall detection experiments, the fall-detection algorithm using the vital sign enables us to detect a fall correctly. Especially, the fall detection algorithm using the vital sign was able to distinguish between a case in which persons did not fall down due to keep their balance although the fall began and a case in which persons fell.

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Among Cervical cord injury, C4 level is tetraplegia. In this study, we support their upper limb motion. As motion intention, we use their Electro Myo Gram (EMG) as motion intention, and support flexion and extension motion at elbow joint by motion assist robot. The subject in this study can exert EMG, but can't control EMG level, as a healthy person can. In this study, we estimate C4 level cervical cord injury patient's motion intention by frequency analysis for EMG signal in real time, and vary the variable coefficient of viscosity's decay rate in admittance controller. Furthermore, the motion assist system compensates EMG signal input based on frequency analysis result while the EMG signal input is stopped against their intention. We conducted the verification experiment about these methods. Using this motion assist method, we support arbitrary upper limb motion of C4 level cervical cord injury patient decline EMG control capability.

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Home oxygen therapy (HOT) is a medical treatment for patients suffering from severe lung diseases. Our ultimate goal is to develop a mobile robot to carry an oxygen tank, which is essential for patients, and follow a patient in an urban outdoor environment. We have proposed a mobile robot with a tether interface to detect the relative position of the foregoing patient. In this paper, we report the questionnaire-based evaluation about the two developed prototypes by the HOT patients. The main results are as follow: The basic following performance is sufficient and the pulling force of the tether is sufficiently small for the patients; The patients prefer the small-sized prototype for compactness and light weight compared with the middle-sized prototype which can carry larger payload; The driving system which we have improved according to the evaluation result satisfies the user needs.

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In the near future due to the aging of society, manual wheelchairs with add-on drives are expected to be used many elderly and handicapped persons because of its folding functions and lighter weight compared with conventional electric wheelchairs. However it needs complex mechanisms and high spec. motors with advanced control technologies for coordinating two drive wheels to rotate correctly. In this paper, a new system using an active-caster is proposed to overcome these problems. The proposed system enabled a manual wheelchair to be moved as same manner as the conventional electric wheelchairs hence it equips single drive wheel. In this paper, the kinematics of the wheelchair with an active-caste is modeled for deriving a control law and analyzing the motion of a motorized wheelchair. The experiments shows expected moving capabilities in the 2DOFs of the wheelchair are controlled independently with no restrictions of a non-holonomic constraint.

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This study develops a "climbing support vehicle for wheelchair." It be able to rig up a commercial wheelchair. It can also reduce the burden on caregivers. Ultimate goal of this study is climbing a slope of 20 degrees. Typically, electric wheelchairs is not able to climb the slope of 10 degrees only. Further This study designed the tilt mechanism of the bearing surface, and the turning system on using a gasoline engine for power. This report describes the details and the design contents of the vehicle to suggest.

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In recent years, power assist equipments are actively researched and developed. Power assist equipments are to assist the muscular strength and the movement of a person. In this study, we aim to develop the power assist equipment which maintains safety and back-drive with the mechanism. However, we have just developed the mechanism for power assistance in vertical direction. Therefore, we develop an arm link mechanism in this paper for constructing power assist equipment.

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Walking plays an important role for elderly to spend their independent daily life. However, aging makes their tibialis anterior muscles to deteriorate, which increase a risk of stumbling and fall down. We aim at developing walking support shoes for elderly people to support their dorsiflexion motion in swing phase by using weight of wearer. A wearer steps a foot pump installed in bottom of shoes and compressed pneumatic energy is temporally stored as an elastic potential energy of a coil spring. Then, torque around foot joint is generated at the moment of toe aparts from a ground using a spring torque. After explaining the structure of the support device and walking principle, we conducted walking experiment to show the effectiveness of the proposed support mechanism.

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While Japan is facing an aging society, the number of people who go to the hospital because of aging, sickness, and accidents is increasing daily. Research on assisting the patients are increasing as well, but research on the upper limb assistance is rather slow compared to the research of lower limb assistance because of the upper limb's complicated structure. We have come up with a system where we can switch from two modes, a mode where the machine rehabilitate the patient and another mode that support the patient on their activities. We have created this machine by the excursion range of human's daily life activities so that the machine can secure the patients arm during their daily activities. We also have created a Control box so that the machine can be easily taken to places. In this paper, we report the characteristics of support functions of this system.

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The revised Variably Configured Wheelchair is proposed, which can travel by escalator safely. The newly designed trapezoidal wheelchair frame controls the location of center of gravity within the safety area. The parallel link mechanism push the lower link by a handle motion to the escalator step surface in order to keep the sheet posture horizontal. The toggle link is applied for magnifying the operation force. The measuring rod attached in front of the wheelchair is pressed against an escalator step side wall in order to set the wheelchair constant distance and to work the parallel link.

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Chest compression is one of the most important actions for Cardio Pulmonary Resuscitation (CPR). Because many people will be survived by the CPR in the early-stage of cardio-respiratory arrest, it is expected chest compression becomes widely known through trainings and workshops. So far, we have proposed a motion optimization method for chest compression based on kinematics and dynamics of a human model. Because body weight is an important parameter achievement chest compression, it is difficult for people of small weight to perform appropriate chest compression. In this paper, we use a mass as an assistant tool for chest compression, and optimize the weight of the mass. By using of the optimized mass, person with the mass will generate the appropriate chest compression.

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Earthquake occurred on March 11, 2011. Many victims were forced to live in shelters. Thus, there are problems such as sleep disorders of the victims because the living in a shelter is poor. In addition, when bedridden elderly people are evacuated, There are a sleeping environmental problem because they can't use high performance electric bed. Therefore, In this study, we propose a air mat system that is able to be used in a shelter. This system uses a pneumatic mat. The mat element has cloth actuator. Therefore, the stiffness of each actuator can be controlled by inner pressure. In this paper, we make basic experiments with using cloth actuator. According to experiment, we clarify the utility of the system.

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This paper describes a novel engine simulator combined with actual piston-crank hardware. The thrust force to the piston generated by engine combustion is given by a cycle by cycle engine simulator including the gas exchange and combustion process simulations. It allows us not only to analyze the elastic effect of the crank shaft but also to study HEV controls because an actual alternative drivetrain is easily connected with the simulator.

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Highly rigid actuators such as a geared motor or hydraulic actuator are widely used in industrial robots. To obtain high-speed motion, it is necessary to increase the actuator output as the robot weight increases. In contrast, humans perform motions with instantaneous force-as in a jump or throw-via variable viscoelastic characteristics. Therefore, we developed a manipulator with variable viscoelastic joint using an artificial muscle and a magnetorheological(MR) brake. Furthermore, we generated instantaneous force, and the dead and rise times decreased compared to the conventional method. In this paper, we controlled the arm position after arbitrary instantaneous force by applying equilibrium of force to the joint. Furthermore, we controlled the arm vibrations by controlling the MR brake using an evaluation function. The results obtained were quite satisfactory.

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A combined electrical motor and Continuously Variable Transmission (CVT) drive system has a wide range of speed-torque characteristic, so that changing the motor's operating speed and CVT's speed ratio according to the load, it is possible to increase the overall efficiency of such a drive system. In this paper we modeled the drive system and performed experiments to derive a method for optimum operation of the drive system.

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Recently, the demand for robots that operate in the fields of nursing and human life have increased due to the aging population and falling birthrates. Since these robots are intended to operate near humans, they are preferable to be light, soft and safe. To satisfy these requirements, we adopt a pneumatic artificial muscle as an actuator of robot manipulator. However, the McKibben-type artificial muscles that are most commonly used have several drawbacks. Therefore, we developed a straight-fiber-type artificial muscle, and developed two degrees of freedom artificial muscle manipulator with a differential gear mechanism. However, the interference occurs in unintended directions in this mechanism because the rotation speed of right and left gears respectively differs. To address this problem, we introduce the disturbance observer (DOB) in the control system. We control the response of right and left gears by disturbance observer and reduce the interference.

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