1. The Key Laboratory of Biomimetic Robots and Systems, Ministry of Education, State Key Laboratory of Intelligent Control and Decision of Complex System, Beijing Advanced Innovation Center for Intelligent Robots and Systems, and School of Mechatronical Engineering, Beijing Institute of Technology 1 , Beijing 100081, China
2. Institute of Intelligent Flexible Mechatronics, Jiangsu University 2 , Zhenjiang 212013, China