Reconfigurable kirigami skins steer a soft robot

Friction-assisted locomotion in limbless creatures has inspired the development of bioinspired soft robots that can creep into narrow passages, inspect disaster sites, and explore unstructured terrains. Directional friction is an essential element of any crawling locomotion where a low forward friction force favors displacement in the direction of movement, and a high backward friction force provides the required anchorage. Kirigami metasurfaces, created by perforating repetitive cuts into thin sheets, can pop out upon being stretched and produce directional friction for specific cut patterns. Here, we create a composite kirigami skin for a soft robot that, in addition to enabling the robot to crawl in a straight line, can reconfigure when stretched along different directions and steer the robot. We fabricated a triangular actuator frame made of three fiber-reinforced extending actuators placed at each edge that, when actuated in pairs, can elongate the frame in three symmetric directions. We covered the actuator with the proposed reconfigurable kirigami skin to create an omnidirectional planar soft crawling robot. We characterized the linear locomotion and maneuvering capabilities of the robot and tracked the robot's trajectories for different combinations of actuation inputs. Our proposed approach uses a single robotics skin to embody multiple locomotion possibilities in soft robots.