1. Institute of Intelligent Flexible Mechatronics, Jiangsu University, Zhenjiang 212013, P. R. China
2. Guodian Nanjing Automation Co., Ltd, Nanjing 210032, P. R. China
3. The Department of Engineering, Science and Macao Institute of Systems Engineering, Macau University of Science and Technology, Macao 999078, P. R. China
4. National Laboratory of Solid State Microstructures, Nanjing University, School of Physics, Nanjing 210093, P. R. China