1. Institute of Robotics & Intelligent Systems, Xi’an Jiaotong University,Shaanxi Key Laboratory of Intelligent Robots,Xi’an,China,710049
2. Xi’an Jiaotong University,School of Energy and Power Engineering,Xi’an,China,710049
3. Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System,Xi’an,China,710049
4. Taiyuan Research Institute of China Coal Technology & Engineering Group Co., Ltd,Taiyuan,China,030006