1. Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong 1 , Shatin, Hong Kong, China
2. State Key Laboratory of Mechanical Transmission, Chongqing University 2 , Chongqing, China
3. Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University 3 , Hong Kong, China
4. Centre for Perceptual and Interactive Intelligence 4 , Shatin, N.T., Hong Kong, China