1. Deep Space Exploration Research Center, Harbin Institute of Technology, Harbin 150001, China e-mail:
2. School of Opto-Electronic Engineering, Changchun University of Science and Technology, Changchun 130022, China e-mail:
3. Reconfigurable Robotics Lab, École Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland e-mail: