Toshihiko Yasuda

One Hand Drive Wheelchair with New Manipulation Mechanism and Assist Functions

A one-hand drive wheelchair with power assist mechanism is developed. We propose a manipulation mechanism with a triple ring and three assist functions, which are power assist function, the maximum velocity limiting function on the downward slope, the reverse prevention function on the upward slope. These functions reduce the physical load of user and improve the safety of the wheelchair. The effectiveness of manipulation mechanism and assist functions is verified through experiments using a prototype, developed in our research group

Power assist effects of a new type assist unit in a one hand drive wheelchair with a triple ring

We have proposed a one hand drive wheelchair with the original manipulation mechanism and the power assist mechanism. Recently, we have developed a new type assist unit, which had a new ON/OFF mechanism constructed by link and sliding mechanism, in order to realize the sure assist torque transformation. During assist, this new assist unit surely keeps the distance of two rollers, which transfer assist torque to tires. In this paper, first, the assist system, including the proposed assist unit, is explained. Furthermore, by using the prototype of the one hand drive wheelchair, implemented new assist units, the effectiveness of power assist function is confirmed, based on running experiments on the flat ground. In this experiment, we have found the following facts: For the user with enough manipulation ability, the power assist effect is week. On the other hand, for the user with inadequate power, the evident power assist effect is observed.

Improvements of manipulation torque transfer mechanism and assist unit for one hand drive wheelchair with a triple ring

We develop a one hand drive wheelchair with original manipulation mechanism and power assist mechanism. In this investigation, first, we improve the transfer mechanism of this wheelchair. As a result, using an improved mechanism, the running resistance of the wheelchair decreased with about 1/2 to the previous one. The effects of this improvement are verified by long distance drive experiment using some one hand drive type wheelchairs. Secondly, we develop the assist unit, which has a new on/off mechanism constructed by link and sliding mechanism, in order to realize the sure assist torque transformation. During assist, improved unit surely keeps the distance of two rollers, which transfer assist torque to tires. Therefore, assist torques, provided by DC motor, are surely transfer to tires.

Mechanism and basic characteristics of a helical inflatable gripper

Weight saving is required at ends of robot arms. This research proposes an extremely lightweight gripper which twines helically. It is composed of an inflatable soft actuator by utilizing plastic films with pleated structures. There are two advantages to the gripper (1) The improvement of the force generated by the increase in the contact area with the target object (2) The ability to twine which is not bound by the object shape. The difference of pneumatic artificial muscles and our researched actuators: (a) Lightweight extremely by using a plastic film, (b) Possible easily to obtain the output by utilizing structural deformation rather than elastic deformation, (c) Difficult to realize the twining movement for elasticity of the rubber. In this paper, we developed a helical inflatable gripper and several characteristics of gripping force are indicated experimentally. From the experimental results, the gripper of the weight of 40[g] achieved the gripping force of 15[N].

Torque measurement experiments of a torque detection mechanism implemented on hand-rims of a one hand drive wheelchair

We have been developed an original one hand drive wheelchair. This wheelchair has the original manipulation mechanism with a triple ring and power assist units, which realize some assist functions, the power assist function, the reverse prevention function on upward slops and so on. Furthermore, we have proposed a simple and useful manipulation torque detection mechanism. In this paper, we demonstrate results of torque measurement experiments, which shows that even if the grasping position of the hand on hand rims changes, the accurate detection of manipulation torque can be realized. The result, presented in this paper, shows the validity of the proposing torque detection mechanism.

Detection mechanism of manipulation torque for one hand drive wheelchair with a triple ring

A one hand drive wheelchair with power assist mechanism is developed. In this investigation, we propose a simple and useful manipulation torque detection method which yields wide detection areas with uniform distribution of stress. This method can be applied to a one hand drive wheelchair with complicated structure of manipulation mechanism with three rings. Moreover, even if the grasping position of the hand on hand rims changes, the accurate detection of manipulation torque can be realized. Therefore, it improves the controllability and the operability of the wheelchair. Numerical results given by FEM show the effectiveness of proposed method.

Proposal of self-transfer assistance system enabling a transfer from the supine position

Some people with physical disabilities have difficulty transferring alone. Many of them want to transfer by themselves without depending on caregivers. We have been advancing research on “self-transfer assistance robot” based on the concept that a care receiver can transfer alone. However, since the self-transfer assistance robot helps transfer from the sitting position to the sitting position, it is difficult for people who cannot take a sitting position alone to use the robot for transferring by themselves. In this research, we propose a transfer from the supine position by “self-transfer assistance system” composed of “self-transfer assistance robot”, newly added “leg assistance robot” and “electric bed assisting the postural change”. In order to realize this system, a part of the self-transfer assistance robot, the leg assistance robot, and the pneumatic soft actuator arranged on the bed were prototyped. Experiments of assistance using them were conducted and it was shown that the transfer from the supine position using this system was feasible.

Strategies for collision prevention of a compact powered wheelchair using SOKUIKI sensor and applying fuzzy theory

For example, there exist some wheelchair users, who cannot operate a powered wheelchair well by using a joystick, which is usual manipulation equipment of powered wheelchairs. A prototype of our group has simple manipulation equipment, constructed by buttons or levers. This operation equipment restricts the running performance of wheelchair. On the other hand, due to the restricted running performance, it is relatively easy to construct operation assist systems, which prevent collisions with obstacles and so on. In this study, the obstacle detection is mainly played by SOKUIKI sensors, which observe the front of the wheelchair. PSD sensors, which observe the side of the wheelchair, play an auxiliary role. We propose strategies for collision prevention using these obstacle observation equipments. Furthermore, we apply fuzzy theory, in order to improve comfortableness of wheelchair user.

Development of soft mechanisms with a pleated ELSA for robots contacting with humans

Recently, studies of entertainment and communication robots have been conducted. These robots require intrinsic safety features because of the many opportunities to contact humans. For example, conventional robot hands that can grasp an object often consist of metal frames, electrical motors, and gears in order to maintain accuracy. These mechanisms are inevitably complex, high weight, and stiff. If the robot hand heavy, the moment of the elementary part of the manipulator is increased. When these robots operate near people, it is also necessary to perform tasks at low speed to ensure the safety of the people. This has the potential of decreasing work efficiency. Therefore, it is desirable for robot hands to be lightweight and soft. We propose extremely lightweight and supple mechanisms using a pneumatic driven thin plastic-film actuator based on pleated structures. In this paper, the structure of a soft gripper with a bending type actuator and a soft parallel joint with a contraction/extension type actuator are proposed. As a basic characteristics of these mechanisms, generating force are experimentally shown. Although this mechanism is lightweight, high output can be expected.

Development of a chained barrel-shaped ELSA for a pneumatic corset aim to prevent a muscle weakening

Recent years, height of percentage of the person who has subjective symptom of such lower back pain is presented as a problem in aging society. Brace therapy is one of the methods of treatment for lower back pain. However, the method of treatment has possibility to cause muscle deterioration by wearing invariably for a corset. On the other hand, it is difficult for such senior citizens and handicapped person to do removable the corset. Therefore, this paper proposed development of the corset that built pneumatic soft actuators and has on/off switching function in order to solve the problem. So we manufactured the corset and the actuators to the corset. And we instituted the EMG experiment to show the performance evaluation of the corset. We found the problem about the responsiveness and we solved the problem by improving a new structure of the actuator. This structure was able to raise the responsiveness.