Dynamic Control of a Manipulator with Passive Joints : Position Control System of a Two-Degree-of-Freedom Manipulator

Abstract

The authors propose a method of controlling the position of a manipulator with passive joints which have holding brakes instead of actuators. In this method, the coupling characteristics of manipulator dynamics are used, and no additional mechanisms are required. In this paper, the effectiveness of the method is verified by experiments using a prototype manipulator. The prototype is a two-degree-of-freedom, horizontally articulated manipulator. The first axis is an active joint and the second axis is a passive joint. While the brake of the passive joist is released, the passive joint is indirectly controlled by the motion of the active joint through the use of dynamic coupling. While the brake is engaged, the active joint is controlled. By combining these two control modes, the total position of the manipulator is controlled. The experiments show that the precise positioning of the passive joint is feasible by use of the proposed method.