1. Ph.D. Candidate, State Key Laboratory of Robotics and System, Harbin Institute of Technology, Xidazhi St., Harbin 150001, P.R. China.
2. Professor, State Key Laboratory of Robotics and System, Harbin Institute of Technology, Xidazhi St., Harbin 150001, P.R. China.
3. Associate Professor, State Key Laboratory of Robotics and System, Harbin Institute of Technology, Xidazhi St., Harbin 150001, P.R. China (corresponding author).