Hideo Hanafusa

Optimal redundancy control of robot manipulators

This paper discusses the optimal redundancy control problem of robot manipulators. The redundancy control problem has mostly been discussed in the framework of instantaneously optimal control. In this paper, the globally optimal redun dancy control problem is solved strictly by using Pontryagins maximum principle. According to the proposed method, the optimal trajectory is necessarily obtained if it evists. If only kinematics is considered, the optimal problem is reduced to minimal value searching in a space of as many dimensions as the degrees of redundancy. If dynamics is also taken into consideration, the optimal problem is reduced to minimum value searching in a space of twice as many dimensions as the degrees of redundancy.

Assistance of self-transfer of patients using a power-assisting device

A power-assisting device is being developed to help older persons and people with disabilities move themselves from beds to wheelchairs. The device is intended to contribute to a more independent life for these people and to greater utilization of their latent abilities. Self-support assistance, i.e., the support provided by a power-assisting device to the person without the need for aid from a caregiver, and capability of the device to assist the movements of the people are discussed. A method for the production of power assistance and motion guidance is then proposed for the device. Finally, a test of the performance of the developed system is described.

Development of an 8 DOF robotic orthosis for assisting human upper limb motion

We developed a robotic orthosis capable of helping human forearm motion. This orthosis was carefully designed such that mechanical safety for human beings could be ensured. A power assist control scheme for the robotic orthosis is proposed. The performance of the developed system is examined by several experiments.

PI type hierarchical feedback control scheme for pneumatic robots

A control scheme for pneumatic drive systems is proposed. In general, static friction, Coulomb friction, and other nonlinear disturbances crucially worsen the performance of pneumatic drive systems. In the proposed control scheme, to guarantee robustness against such disturbances and stability of the motion, position feedback loops and pressure feedback loops are hierarchically connected. The stability of the motion is investigated by using a Lyapunov function. As a result, it is mathematically proven that the motion of pneumatic drive systems converges to a fixed desired point as time tends to infinity, even if the disturbances affect the motion. The effectiveness of this control scheme is demonstrated through some experimental results.<<ETX>>

Development of a power assistive device for self-supported transfer motion

A power-assisting device is presented to help elderly patients and patients with disabilities transfer themselves from beds to wheelchairs. The device is intended to contribute to a more independent life for the patients and to greater utilization of their disabilities. The development of the device, which consists of an upper part capable of motion in a horizontal plane and a lower part capable of motion in a vertical plane, is discussed. The production method for the power assistance and motion guidance of this device is proposed. Finally, the testing of the performance of the developed system in a basic experiment is described.

Cooperative control of dual-arm robots for reasonable motion distribution

This paper proposes a cooperative control scheme of dual-arm robots, which produces a reasonable pair of the two endpoint motions of the arms for a given relative motion. A dual-arm system with a linear motion is discussed, and the principle of the control scheme is presented. The redundancy of the system and the problem of the motion distribution are explained. The concept of the absolute motion which represents the total motion of the system is introduced, and a cooperative control scheme of dual-arm robots is proposed, using this absolute motion. Basic equations are presented and a cooperative control scheme of dual-arm robots with six degrees of freedom is proposed. Finally, several simulation and experimental results are given to illustrate the validity of the proposed control scheme.