1. Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China
2. Department of Systems and Control Engineering, Tokyo Institute of Technology, Tokyo 152-8550, Japan
3. Research Fellow of Japan Society for the Promotion of Science (JSPS), Tokyo 102-0083, Japan
4. Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0014, Japan
5. Department of Mechanical Engineering, Tokyo University of Science, Chiba 278-8510, Japan
6. Faculty of Advanced Engineering, Tokyo University of Science, Tokyo 125-8585, Japan