Dexterous motion design for a DD parallel robot

This paper deals with design of a dexterous motion for a robot consisting of a six degrees-of-freedom (DOF) closed kinematic chain, and driven by direct-drive (DD) motors. The robot can move very fast and, therefore, the motion is not only dexterous but also very fast. The paper considers, first, a set of control modes that are necessary and sufficient for the implementation of the dexterous motion. Then, a control program is designed for the implementation of the control modes, in which exploitation of the motor back-drivability and compensation of the motor friction, plays a key role. The paper also discusses a teaching program, based upon which an off-line teaching system has been implemented; dexterous tasks such as peg-insertion and side-matching, which are very fast, have been taught by the system successfully.