1. College of Electrical and Information Engineering, Lanzhou University of Technology, Lanzhou, People's Republic of China
2. College of Computer and Communication, Lanzhou University of Technology, Lanzhou, People's Republic of China
3. National Demonstration Center for Experimental Electrical and Control Engineering Education, Lanzhou University of Technology, Lanzhou, People's Republic of China
4. School of Automation and Electrical Engineering, University of Science and Technology Beijing, Beijing, People's Republic of China