1. State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
2. School of System Engineering, Kochi University of Technology, Kochi, Kami, Japan
3. National Research Center for Rehabilitation Technical Aids, Beijing, China
4. Department of Mechanical Engineering, University of Bath, Bath, U.K
5. State Key Laboratory of Robotics and System, Harbin Institute of Technology (HIT), Harbin, China