1. Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
2. Department of Electrical and Electronic Engineering, Tottori University, 4-101 Koyama-Minami, Tottori 680-8552, Japan
3. Brain Science Inspired Life Support Research Center, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan