1. a Bio-Mimetic Control Research Center, The Institute of Physical and Chemical Research, 8-31, Rokuban 3-chome, Atsuta-ku, Nagoya 456, Japan
2. b Bio-Mimetic Control Research Center, The Institute of Physical and Chemical Research, 8-31, Rokuban 3-chome, Atsuta-ku, Nagoya 456, Japan, Department of Electric Engineering, Faculty of Engineering, Chubu University, 1200, Matsumoto-cho. Kasugai 487, Japan
3. c Department of Electronic Engineering, Aichi Institute of Technology, 1247 Yakusa-cho, Toyota 470-03, Japan
4. d Bio-Mimetic Control Research Center, The Institute of Physical and Chemical Research, 8-31, Rokuban 3-chome, Atsuta-ku, Nagoya 456, Japan, Department of Information and Computer Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi 441, Japan