1. College of Automation, Chongqing University, Chongqing 400044, China.
2. College of Automation, Chongqing University, Chongqing 400044, China and Key Laboratory of Complex System Safety and Control, Ministry of Education. (e-mail: su7558@qq.com)
3. Department of Electrical and Computer Engineering, University of Auckland, Auckland 1010, New Zealand.
4. College of Automation, Chongqing University, Chongqing 400044, China and Key Laboratory of Complex System Safety and Control, Ministry of Education.