1. Department of Mechanical Engineering; The University of Hong Kong; Pokfulam Road Hong Kong
2. School of Automation; Nanjing University of Science and Technology; Nanjing P.R. China
3. National Center for Mathematics and Interdisciplinary Sciences; Academy of Mathematics and Systems Science; Chinese Academy of Sciences; Beijing 100190 P. R. China
4. Tianjin Key Laboratory of Process Measurement and Control; School of Electrical Engineering and Automation; Tianjin University; Tianjin 300072 P. R. China
5. Department of Electronic Engineering; City University of Hong Kong; Kowloon Hong Kong