It is thought that the dynamic motions with lower limbs such as walking can be made more effectively by moving each joint along to its natural frequency. If the natural frequency were able to be modified purposefully, the effective motion could be performed at any angular frequency around joint. We realized that with the exoskeleton-type powered suit, HAL (Hybrid Assistive Leg)-3 we developed for walking aid. In this research, we considered the operator’s leg as pendulum model, identified the physical parameters around human’s knee joints, tried to adjust the impedance, and applied that to pendular movement of leg. The effectiveness of adjusting the natural frequency in power assist control can be confirmed through the experiments evaluated with myoelectricity.

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The effectiveness of a robotic training device was evaluated in a 24-year-old male, cervical level four, ASIA Impairment Scale D injury. Robotic training of both upper extremities was provided for three hr/day for ten consecutive sessions using the RiceWrist, an electrically-actuated forearm and wrist haptic exoskeleton device that has been designed for rehabilitation applications. Training involved wrist flexion/extension, radial/ulnar deviation and forearm supination/pronation. Therapy sessions were tailored, based on the patient’s movement capabilities for the wrist and forearm, progressed gradually by increasing number of repetitions and resistance. Outcome measures included the ASIA upper-extremity motor score, grip and pinch strength, the Jebsen-Taylor Hand Function test and the Functional Independence Measure. After the training, improvements were observed in pinch strength, and functional tasks. The data from one subject provides valuable information on the feasibility and effectiveness of robotic-assisted training of forearm and hand functions after incomplete spinal cord injury.

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Backdrivability is a keyword with rising importance, not only in humanoid robots, but also to wearable robots. Power assist robots, namely exoskeletons are expected to provide mobility and independence to elderly and people with disability. In such robots, without backdrivability, error between human and robot motion can be painful; sometimes dangerous. In this research, we apply a type of hydraulic actuator, specially designed to realize backdrivability, to exoskeletal robot to improve backdrivability. We present the basic methodology to apply such hydraulic actuator to wearable robots. We developed prototype of knee joint power assistexoskeleton and performed fundamental tests to verify the design method validity.

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Many researchers are studying and developing various kinds of man-machine systems. Especially, a wearable robot, such as anexoskeleton power suit, is one of the most remarkable fields. In this field, more accurate and reliable sensing system for detecting human motion intention is strongly required. In most of conventional man-machine systems, torque sensors, tactile pressure sensors and EMG sensors are utilized in a man-machine interface to detect human motion intention. These sensors, however, have some limitations. For example, it is hard to install and secure torque sensors on the joints of a human body. It is not easy to correlate the data from a tactile pressure sensor to the human motion intention. Although the EMG sensor can detect human motion intention, the sensor system is complex and expensive, and suffers from electric noise. We have been developing an innovative sensor suit which, just like a wet suit, can be conveniently put on by an operator to detect his or her motion intention by non-invasively monitoring his or her muscle conditions such as the shape, the stiffness and the density. This sensor suit is made of soft and elastic fabrics embedded with arrays of MEMS sensors such as strain gauges, ultrasonic sensors and optical fiber sensors, to measure different kinds of human muscle conditions. In the previous paper, the muscle stiffness sensor for detecting muscular force was developed according to the fact that the muscle gains its stiffness as it is activated. Its superior performance was reported through experiments in which the sensor was applied for the assisting device for the disable. In this paper, the ultrasonic sensor disk is proposed as one of the sensor disks embedding the sensor suit. This sensor is based on an original principle and non-invasively detects activity of specific muscle. It is clear that the square of ultrasonic transmission speed is in proportion to the elasticity of the object and in inverse proportion to the density. It is estimated that the elasticity and density of the muscle increase or decrease as the muscle is energized. Then, it is hereby expected that the muscular activity is measured by the ultrasonic sensor. In this study, the feasibility of an ultrasonic sensor for detecting muscular force is shown thr- ough experiments.

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The following topics are dealt with: medical robotics; nanobiotechnology; regenerative medicine; human-machine interaction; exoskeleton; rehabilitation medicine; prosthesis; biomimetics; surgery; and patient diagnosis.

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