Overhead snapshots. Overhead snapshots. (A to E) Mark I3, robot experiments (movie S1). (F) Mark I3, simulation (movie S2, side by side with a run on the robots). (G) Mark I4, simulation (movie S4). (H) Mark II3, simulation (movie S5). (I) Mark II4, simulation (movie S6). Lorenzo Garattoni, and Mauro Birattari Sci. Robotics 2018;3:eaat0430 Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works