1. School of Mechatronic Engineering, Beijing Institute of Technology, Beijing 100081, China
2. Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing 100081, China
3. Key Laboratory of Biomimetic Robots and Systems of Chinese Ministry, Beijing Institute of Technology, Beijing 100081, China
4. Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Roma, Italy