1. e-mail:
2. e-mail: Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
3. Research Institute of Intelligent Control and Systems, Harbin Institute of Technology, Heilongjiang, Harbin 150080, China e-mail:
4. Institute of Control Systems, Hamburg University of Technology, Hamburg 21073, Germany e-mail:
5. Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China e-mail: