1. School of Information and Control Engineering, Qingdao University of Technology, Qingdao 266520, China
2. State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University, Hangzhou 310027, China
3. School of Automation, Central South University, Changsha 410012, China
4. College of Marine Electrical Engineering, Dalian Maritime University, Dalian 116026, China