1. Department of Precision Engineering, School of Engineering, The University of Tokyo: 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2. Laboratory of Human Evolutionary Biomechanics, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Japan
3. Research into Artifacts, Center for Engineering (RACE), School of Engineering, The University of Tokyo, Japan