1. Research Institute of Robotics, School of Mechanical Engineering, Shanghai JiaoTong Univ., 800 Dongchuan Rd., Shanghai 200240, People’s Republic of China (corresponding author).
2. Research Institute of Robotics, School of Mechanical Engineering, Shanghai JiaoTong Univ., 800 Dongchuan Rd., Shanghai 200240, People’s Republic of China.
3. Research Center of Intelligent Maintenance Systems, Univ. of Cincinnati, P.O. Box 210072, Cincinnati, OH 45221.