1. a ERATO Kitano Symbiotic Systems Project, Japan Science and Technology Corp., Suite 6A, M-31, 6-31-15 Jinguumae, Shibuya, Tokyo 150-0001, Japan, Sony Computer Science Laboratory. 3-14-13 Higashi-Gotanda, Shinagawa, Tokyo 141, Japan
2. b Adaptive Machine Systems, Graduate School of Engineering, Osaka University, Yamadaoka, Suita, Osaka 565-0871 Japan