From mindless active particles to buckling-mediated intelligent robots

A key advantage of soft robots is their non-rigid, compliant exterior, enabling them to adapt to unknown, complex environments. Vital to this adaptability is the autonomous physical intelligence embodied in the materials used to construct soft robotic devices. Prior work has investigated the motion of soft robots constructed from designed smart materials that react to environmental heat or moisture. This work presents a simple but adaptable mode of physical intelligence. To each end of a thin, elastic beam, we attach a centimeter-scale active matter particle acting as a model engine. These particles buckle the beam that joins them and are found to run across the substrate onto which they sit. More surprisingly, these runners are observed to be able to navigate simple mazes. Here we rationalize the system's mechanics and leverage this new knowledge to systematically characterize its interactions inside the maze, e.g., making turns and passing through constrictions. As many soft robots incorporate elastic components, this work may inform the use of elasticity and active elements in navigating unstructured environments in such devices.