1. College of Mechanical Engineering and Automation, Huaqiao University, Xiamen, Fujian, China
2. College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao, China
3. College of Control Science and Engineering, Shandong University, Jinan, China
4. Department of Electronic and Information Systems, Shibaura Institute of Technology, Saitama, Japan