1. Southern University of Science and Technology Shenzhen Key Laboratory of Intelligent Robotics and Flexible Manufacturing Systems, , Shenzhen 518055 , China ;
2. DR Robotics Ltd. , Hengqing, Zhuhai 519031 , China
3. Kings College London, University of London Center for Robotics Research, Department of Engineering, , Strand, London WC2R 2LS , UK