1. School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou 221116, China
2. School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou 221116, China;
3. Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109;
4. Jiangsu Key Laboratory of Mine Mechanical and Electrical Equipment, China University of Mining and Technology, Xuzhou 221116, China e-mail: