1. Graduate School of Engineering, Hokkaido University, Sapporo, Japan
2. Kawasaki Railcar Manufacturing, Kobe, Japan
3. Department of Robotics, School of Engineering, Tohoku University, Sendai, Japan
4. Faculty of Engineering, Kitami Institute of Technology, Kitami, Japan
5. Faculty of Engineering, Hokkaido University, Sapporo, Japan
6. National Institute of Technology, Tomakomai College, Tomakomai, Japan