This paper describes an efficient design method for dynamic compliance control by taking the advantages of direct drive. First we analyze dynamic bchavior of compliance control system having force/ torque sensors attached to various locations such as wrists, arm joints and actuators. Pole-zero locations and natural frequencies as well as stability issues are compared for each control system. It is shown that the dynamic performance depends on the strucural stiffness and mass distribution as

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... as relative locations of actuators and sensors. An efficient structure of mechanical construction and actuator-sensor locations is then drived. An optical torque sensor built in a direct-drive motor is developed on the basis of the analysis. The compliance control system equipped with the torque sensor is synthesized in such a way that an arbitrary compliance be accommodated while placing all the poles at arbitrary locations. It is shown through experiments that the compliance of the torque control system can be varied from a small value to an extremely large value without sacrifice of the system stability.