1. Department of Manufacturing Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P.R. China
2. Department of Industrial Equipment and Control Engineering, South China University of Technology, Guangzhou 510641, P.R. China
3. Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Hum, Kowloon Hong Kong, P.R. China
4. Hong Kong Plastic Technology Center, Kowloon, Hong Kong, P.R. China