Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan.|Department of Informatics, Bioengineering, Robotics and Systems Engineering, Università degli studi di Genova, Genova, Italy.|CNRS-AIST JRL (Joint Robotics Laboratory), UMI3218/RL, Umezono, Tsukuba, Ibaraki, Japan.|Department of Informatics, Bioengineering, Robotics and Systems Engineering, Università degli studi di Genova, Genova, Italy.|Department of Bioengineering, Imperial College of Science, Technology and Medicine, South Kensington, London, United Kingdom.