Harnessing Cascading Dominoes for Peristaltic Wave Motion

Organisms have evolved many simple yet effective muscular movements. Of these, peristaltic wave motion is among the most prolific and can be found across organism scales and in a variety of organs that transport objects or provide locomotion. Several robotic platforms have mimicked peristaltic movement, which resembles soliton propagation; however, the complexity of integrating multiple sequential actuators and the fragility of these systems have limited their practical application. In this work, we demonstrate the potential of cascading dominoes to realize soliton-like wave movements that can transport objects and locomote with only two actuators. Unlike conventional domino series where falling dominoes produce a soliton at the collapsing frontier, we added a revolute joint on each domino to ensure all the dominoes stack continuously, which inherently changes the soliton wave shape. We show how domino geometry determines the wave shape of the soliton, both analytically and experimentally, and how actuator speed affects the wave speed. Inspired by peristaltic wave motion in living organisms, we used the cascading dominoes to move objects through an artificial esophageal conduit and build a “mantis shrimp” crawler. Cascading dominoes enable a new type of actuator mechanism and provide new opportunities for robotic motion.