1. a Yaskawa Electric Co., 5-9-10, Tokodai, Tsukuba, Ibaraki, 300-2635, Japan
2. b Yaskawa Electric Co., 5-9-10, Tokodai, Tsukuba, Ibaraki, 300-2635, Japan
3. c Yaskawa Electric Co., 5-9-10, Tokodai, Tsukuba, Ibaraki, 300-2635, Japan
4. d Tsukigase Rehabilitation Center, Keio University, 380
5. e Tsukigase Rehabilitation Center, Keio University, 380
6. f Faculty of Science and Technology, Keio University