Cooperative Compliant Motion Control of Writ and Arm
Kei Kawase, Hiroshi Ishikawa, Chihiro Sawada, and Masayuki Takata
IBM JAPAN Ltd., Tokyo Research Laboratory Dai 36 Kouwa Bldg., 5-19 Sanbancho, Chiyoda-ku, Tokyo 102, Japan
This paper describe a method for high-speed compliance control by cooperation between an arm and a wrist body. To realize high-speed compliance control, it is necessary to reduce the endpoint inertia. The proposed method alleviates this problem by physically reducing the endpoint inertia, introducing a discreet wrist body, which is set up at the end of the arm, and by cooperative control between them. The wrist can generate a highspeed compliance because of its low inertia. However, the wrist’s range of motion is restricted within a small range. We developed a method to solve this problem. The wrist can generate a desired compliance, and the arm expands the wrist’s range of motion. Consequently, the wrist-and-arm system can achieve compliant motion beyond the wrist’s range of motion with multi degrees of freedom. We analyzed the behavior of the proposed wrist-and-arm system and compared it with the conventional method using force sensor feedback. This control method is implemented in a prototype system. We had experiments to evaluate our method by touching the cyclic displacement. We confirm the effectiveness of the cooperative control method by the results. They showed that our cooperative control method can expand wrist’s range of motion.