1. School of Astronautics, Harbin Institute of Technology, Harbin, P.R. China
2. Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong
3. School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen, P.R. China
4. Department of Mechanical Engineering, University College London, London, UK
5. The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, P.R. China