1. Ningxia Engineering Research Center for Hybrid Manufacturing System, 204th Wenchang North Street, Xixia District, Yinchuan 750021, China
2. School of Electrical and Information Engineering, North Minzu University, 204th Wenchang North Street, Xixia District, Yinchuan 750021, China
3. College of Mechatronic Engineering, North Minzu University, 204th Wenchang North Street, Xixia District, Yinchuan 750021, China
4. Department of Mechanical Engineering, University of Kansas, 3138 Learned Hall, 1530 W. 15th Street, Lawrence, KS 66045-4709, USA