1. Ph.D. Student, State Key Lab of Fluid Power Transmission and Control, Zhejiang Univ., Hangzhou 86-310027, China (corresponding author).
2. Professor, State Key Lab of Fluid Power Transmission and Control, Zhejiang Univ., Hangzhou 86-310027, China.
3. State Key Lab of Fluid Power Transmission and Control, Zhejiang Univ., Hangzhou 86-310027, China.
4. Ph.D. Student, State Key Lab of Fluid Power Transmission and Control, Zhejiang Univ., Hangzhou 86-310027, China.