1. Department of Intelligent Mechatronics, Akita Prefectural University, Akita, Japan
2. Department of Precision Engineering, The University of Tokyo, Tokyo, Japan
3. Department of Precision Mechanics, Chuo University, Tokyo, Japan
4. Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
5. Mazda Motor Corporation, Yokohama, Japan
6. Mazda Motor Corporation, Hiroshima, Japan