1. State Key Laboratory of Mechanical Transmissions, School of Automobile Engineering, Chongqing University, Chongqing 400044, China; Department of Mechanical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 e-mail:
2. State Key Laboratory of Mechanical Transmissions, School of Automobile Engineering, Chongqing University, Chongqing 400044, China
3. Department of Mechanical Engineering, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 e-mail: