DYNAMIC CONTROL OF A MANIPULATOR WITH PASSIVE JOINTS IN OPERATIONAL SPACE

We present a method to control a manipulator with passive joints, whic h have no actuators, in operational space. The equation of motion is d escribed in terms of operational coordinates. The coordinates are sepa rated into active and passive components. The acceleration of the acti ve components can be arbitrarily adjusted by using the coupling charac teristics of manipulator dynamics. This method is also extended to pat h tracking control of a manipulator with passive joints. A desired pat h is geometrically specified in operational space. The position of the manipulator is controlled to follow the path. In this method, a path coordinate system based on the path is defined in operational space. T he path coordinates consist of a component parallel to the path and co mponents normal to the path. The acceleration of the components normal to the path is controlled according to feedback based on tracking err or by using the dynamic coupling among the components. This in turn ke eps the manipulator on the path. The effectiveness of the method is ve rified by experiments using a two-degree-of-freedom manipulator with a passive joint.