1. a Graduate School of Creative Science and Engineering, Waseda University, 41-304, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan;, Email: k-hashimoto@takanishi.mech.waseda.ac.jp
2. b Department of Mechanical Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama, Kanagawa 221-8686, Japan; Humanoid Robotics Institute (HRI), Waseda University, 41-204A, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan
3. c Humanoid Robotics Institute (HRI), Waseda University, 41-204A, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan; Department of Modern Mechanical Engineering, Waseda University, TWIns Room 3C-202, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan