1. Guangdong R & D Center for Technological Economy RM. 802, Guangzhou, Guangdong, P.R. China
2. Guangdong Key Laboratory of Modern Control Technology, Institute of Intelligent Manufacturing, Guangdong Academy of Sciences, Guangzhou, Guangdong, P.R. China
3. School of Engineering, Swansea University, Swansea, UK
4. Foshan Tri-Co Intelligent Robot Technology Company Ltd., Foshan, China