1. Guangdong Province Key Laboratory of Precision Equipment and Manufacturing Technology, South China University of Technology, Guangzhou, Guangdong 510640, China e-mail:
2. Professor Guangdong Province Key Laboratory of Precision Equipment and Manufacturing Technology, South China University of Technology, Guangzhou, Guangdong 510640, China e-mail:
3. Division Microrobotics, Department of Computing Science, University of Oldenburg, Uhlhornsweg 84, A1, Oldenburg 26111, Germany e-mail: