Position and Force Control of Multi-fingered Robot Hand and Its Application to Massage Motion

P. Minyong, T. Miyoshi, and H. Kitagawa (Japan)

Keywords

Multifingered robot, Massage system, Motion control, Po sition control, Force control

Abstract

In this paper, a massage motion control system comprised of position control and force control in a multi-fingered robot hand is presented. The finger position control from the initial position of the multi-fingered robot hand to a tar get position of the objects for massage was achieved by using an algorithm which converted the desired fingertip trajectory into the desired angle of links in each finger by means of inverse kinematics. Its controller was used un til the robot hand contacted the objects for massage. Af ter contact was made, the fingertip position control was switched to a force control position needed to apply pres sure for the massage. The first step which the expert mas sage robot performs is "Pushing," which is controlled by the fingertip force control realized by the humanoid-type robot hand. The fingertip forces exerted by an expert hu man therapist was measured using sheet distribution pres sure sensors, and the datas obtained was recorded in a com puter. After the measurements were taken, the human ex pert's fingertip force was reproduced by the robot hand. The fingertip force of the robot hand was controlled us ing feedback obtained with a 6-axis force sensor. To make the force of each fingertip of the four-fingered robot hand track to the fingertip force exerted by the expert human massage therapist, PI servo compensation and a Jacobian matrix were applied. Through simulation and experiments, the usefulness of the proposed control systems was demon strated.

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