1. Department of Mathematics, Jining University, Qufu, Shandong 273155, China; School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200072, China
2. School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200072, China
3. School of Mechanical and Mechatronic Engineering, University of TechnologySydney, Ultimo, NSW 2007, Australia