1. Sydney Institute for Robotics and Intelligent Systems and Australian Center for Field Robotics, School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Darlington, Australia.
2. Department of Mechanical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore.
3. Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore.
4. Department of Control Science and Engineering, College of Electronics and Information Engineering, Tongji University, Shanghai, China.