Topological Solitons Make Metamaterials Crawl

In recent years, the ability to propagate topological solitons in mechanical metamaterials has unlocked unpaved paths towards potential applications in wave propagation, mechanical logic, and shape morphing. Here, we demonstrate how a multistable metamaterial can harness topological solitons with coupled rotational and translational components and become, itself, a crawling robot. We start by characterizing the topological solitons via experimental measurements and analysis. We then use their rotational component to produce a favorable gradient of friction between the metamaterial and the underlying substrate. This, in turn, creates locomotion. Previously proposed crawling robots usually require complex control of multiple actuators. In contrast, our robot can be powered by a single actuator, and all features needed for locomotion are embedded in the mechanics and activated by the topological solitons.