Development of Measurement System for Quantitative Evaluation of Skillfulness of Lower Extremities. - Kazunori Yamazaki; Dongjun Jin; Yoshifumi Morita; Noritaka Sato; Hiroyuki Ukai; Kenji Kozakai; Satoru Shibata; Shigenori Onishi; Akihiro Ito; Daisuke Mizuno; Tatsuya Hirai; Haruna Takeda; et al. (J. Robotics Netw. Artif. Life, 2014)