1. State Key Lab of Fluid Power Transmission and Control, Department of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China e-mail:
2. Mem. ASME Mechanical Engineering, University of Michigan, 1043E HH Dow, 2300 Hayward St., Ann Arbor, MI 48109 e-mail:
3. Mem. ASME Mechanical Engineering, University of Michigan, 1043A HH Dow, 2300 Hayward St., Ann Arbor, MI 48109 e-mail:
4. UM-SJTU Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China e-mail:
5. Fellow ASME Mechanical Engineering and Biomedical Engineering, University of Michigan, 3001E EECS, 2350 Hayward St., Ann Arbor, MI 48109 e-mail: