1. Department of Mechanical Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu 400-8511, Yamanashi, Japan
2. Diver Technology Corporation, Project Research Center 205, University of Yamanashi, 4-3-11 Takeda, Kofu 400-8511, Yamanashi, Japan
3. Suzuki Motor Corporation, 300 Takatsuka, Chuo, Hamamatsu 432-8611, Shizuoka, Japan