1. Faculty of Mechanical and Electrical Engineering Guizhou Normal University Guiyang Guizhou China
2. Department of Automation Shanghai Jiao Tong University Shanghai China
3. Department of Electrical and Computer Engineering University of Macau Macau China
4. Faculty of Mechanical Engineering Guizhou University Guiyang Guizhou China
5. Department of Electromechanical Engineering University of Macau Macau China
6. On leave from the Instituto Superior Técnico Universidade de Lisboa Lisbon Portugal