Torque optimization for a 7DOF upper-limb power-assist exoskeleton robot

Abstract

Many kinds of power-assist robots have been developed in order to assist daily life motions of the elderly or physically weak persons. A human upper-limb has 7 degrees of freedom to achieve various tasks dexterously. Therefore, to assist all upper-limb joint motions of a human, the upper-limb power-assist robot is required to have 7DOF. On the other hand, to achieve a desired task, a person moves own hand to the desired position and orientation. For this reason, the hand position or hand force must be focused to be controlled by the upper-limb power-assist robots. However, the hand position or hand force is 6-dimensional vector, so the 7DOF upper-limb power-assist robot has a redundancy and in general, a pseudo-inverse matrix is used in the control. In this paper, the torque optimization for an upper-limb power-assist exoskeleton robot using the pseudo-inverse matrix is discussed. The effectiveness of the proposed method was evaluated by the experiments.