1. Department of Computer Science and Technology, Tsinghua University, Beijing, China
2. College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing, China
3. Laboratory for Embedded System and Intelligent Robot, Wuhan University of Science and Technology, Wuhan, China
4. Department of Mechanical Engineering, Anhui University of Technology, Anhui, Maanshan, China
5. National Research Center for Rehabilitation Technical Aids, Beijing, China