1. Department of Mechanical Engineering, University of South Carolina, 300 Main Street, Columbia, South Carolina 29208, United States
2. College
of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
3. Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824-1226, United States
4. Institute
of Robotics and Intelligent Systems, ETH Zurich, CH-8092 Zurich, Switzerland
5. Department of
Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904-4746, United States