1. Key Laboratory for Biomechanics and Mechanobiology of Ministry of EducationSchool of Biological Science and Medical EngineeringBeihang University Beijing 100083 P. R. China
2. School of Life Information Science and Instrument EngineeringHangzhou Dianzi University Hangzhou 310018 Zhejiang Province P. R. China
3. Beijing Advanced Innovation Centre for Biomedical EngineeringBeihang University Beijing 100083 P. R. China
4. National Research Center for Rehabilitation Technical Aids Beijing 100176 P. R. China