1. Robotic Institute, Beihang University, Beijing 100191, China
2. Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age Disability and Key Laboratory of Rehabilitation Aids Technology and System of the Ministry of Civil Affairs, National Research Center for Rehabilitation Technical Aids, Beijing 100176, China
3. Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
4. Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China