Lee, SooyongAdvanced Robotics Research Center, Korea Institute of Science and Technology, PO Box 131, CheongRayng, Seoul, Korea, Department of Electrical Engineering, Texas A &M University, College Station, TX 77843-3112, USA Kim, MunsangAdvanced Robotics Research Center, Korea Institute of Science and Technology, PO Box 131, CheongRayng, Seoul, Korea Lee, Chong-WonAdvanced Robotics Research Center, Korea Institute of Science and Technology, PO Box 131, CheongRayng, Seoul, Korea