1. a School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798
2. b School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798
3. c Department of Mechanical Engineering and Centre for Intelligent Machines, McGill University, Quebec, Canada H3A 2K6
4. d School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798