1. Department of Mechanical Engineering, University of Michigan, 2350 Hayward, Ann Arbor, MI 48109, USA.
2. Department of Robotics, University of Michigan, 2505 Hayward, Ann Arbor, MI 48109, USA.
3. X, the Moonshot Factory, 100 Mayfield Ave., Mountain View, CA 94043, USA.
4. Robotics at Google, 1600 Amphitheatre Parkway, Mountain View, CA 94043, USA.
5. Georgia Institute of Technology, 85 Fifth Street NW, Atlanta, GA 30308, USA.