1. Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
2. School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
3. Shaanxi Key Lab of Intelligent Robots, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China