1. Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore
2. U.S. Army RDECOM-TARDEC, Development and Engineering Center, Joint Center for Robotics, 6501 E. 11 Mile Road, Warren, MI 48397-5000, USA
3. UTA Research Institute, University of Texas at Arlington, 7300 Jack Newell Boulevard South, Fort Worth, TX 76118, USA