1. State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China
2. Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110016, China
3. University of Chinese Academy of Sciences, Beijing 100049, China
4. Institute of Urban Rail Transportation, Southwest Jiaotong University, Chengdu 610000, China
5. Department of Mechanical Engineering, City University of Hong Kong, Hong Kong SAR, China