Speed/Force Control of 4-Actuator Plane Type Parallel Mechanism by Using Internal Force with Redundant Degree of Freedom

摘要

This paper describes speed/force control of a plane-type parallel link mechanism with redundant degree of freedom. Parallel mechanisms contain problems of joint clearances. Joint clearances reduce stiffness of the mechanism and cause errors of control accuracy by the effect of external forces from the environment. We propose control systems including internal force in order to overcome these problems. The internal force can reduce errors caused by joint clearance and improve the stiffness of mechanism. We apply the proposed method to a 4-aetuator plane-type parallel link mechanism composed of a couple of 2-DOF link with a rotary actuator and a linear actuator. The ultrasonic motor is applied to the linear actuator in order to construct the compact and light-weight mechanism. This paper presents the effectiveness of the proposed method by experiments of speed/force hybrid control, and of trajectory control by model-based adaptive control.