1. Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, Canada
2. Institute of Robotics and Mechatronics, DLR – German Aerospace Center, Wessling, Germany
3. Department of Electrical Engineering and Information Technology, Technical University of Munich, Munich, Germany
4. Department of Mechano-Informatics, University of Tokyo, Bunkyo-ku, Tokyo, Japan