Position control system of a two degree of freedom manipulator with a passive joint

A method is proposed for controlling the position of a manipulator with passive joints that have holding brakes instead of actuators. In this method, the coupling characteristics of manipulator dynamics are used, and no additional mechanisms are required. The effectiveness of the method was 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 joint 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 use of this method makes the precise positioning of the passive joints possible