1. Electromechanical Engineering Technology Department, California State Polytechnic University, Pomona, California 91768, USA
2. Department of Mechanical Engineering, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
3. Department of Mechanical and Aerospace Engineering, Brunel University London, Uxbridge UB8 3PH, UK
4. Mobility and Robotic Systems, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109-8099, USA