1. State Key Laboratory of Tribology & Institute of Manufacturing Engineering, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
2. Beijing Key Laboratory of Precision/Ultra-Precision Manufacturing Equipments and Control, Tsinghua University, Beijing 100084, China
3. Department of Mechanical Engineering, McGill University, Montreal, H3A 0G4, Canada
4. Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada