Harnessing topological vector solitons for locomotion

The propagation of topological solitons in mechanical metamaterials has attracted significant attention not only for its rich physics, but also for the wide range of potential applications, including unidirectional wave propagation, mechanical logical computation, and shape morphing. In this work, we exploit the vectorial nature of topological solitons supported by metamaterials based on a rotating squares mechanism to build crawling robots. We first use a combination of experimental measurements and analysis to characterize the topological solitons. We then show that by harnessing their rotational component to modify the friction between the metamaterial and the underlying substrate, locomotion becomes possible. Unlike previously proposed crawling robots that require complex input control of multiple actuators, a simple, slow input signal suffices to make our system crawl. All features required for locomotion are embedded into the architecture of the metamaterial and sequentially activated by the topological solitons.