1. School of Reliability and Systems Engineering, Beihang University, Beijing 100191, China
2. Department of Automation, University of Science and Technology of China, Hefei 230027, China
3. Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
4. Research Institute of Intelligent Control and Systems, Harbin Institute of Technology, Harbin 150001, China