1. Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo University of Agriculture and Technology, Koganei Campus, Tokyo 184-8588, Japan
2. CNRS-AIST JRL (Joint Robotics Laboratory) IRL, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8560, Japan
3. Naver Labs Europe, 38240 Meylan, France
4. Department of Mechanical Engineering, Graduate School of Engineering, The University of Tokyo, Hongo Campus, Tokyo 113-8654, Japan