1. School of Automation, Beijing Institute of Technology, Beijing, China
2. School of Information and Control Engineering, China University of Mining and Technology, Xuzhou, China
3. State Key Laboratory of Robotics and System, School of Mechanical Engineering and Automation, Harbin Institute of Technology at Shenzhen, Shenzhen, China
4. Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong, China