N.F. Law and R. Chung
Department of Electronic and Information Engineering,
The Hong Kong Polytechnic University,
Hung Hum, Kowloon, Hong Kong.
Department of Mechanical and Automation Engineering,
The Chinese University of Hong Kong,
Shatin, N.T., Hong Kong.
Email : ennflaw@polyu.edu.hk, rchung@mae.cuhk.edu.hk