Soft Robot Locomotion with Metachronal Waves

Abstract

Conventional robots adopt wheels or robotic limbs for locomotion. Wheels are simple to control but not suitable for irregular terrains. On the other hand, robotic feet can overcome a wider variety of surfaces but are less desirable due to their complex design and control system. In nature, we find that invertebrate animals, like snails, can go anywhere without needing the complex control system a rigid robot needs. Instead, they move forward by sending travelling deformations along their soft bodies. Inspired by these animals, we present a soft robot that uses a sequence of deformations for locomotion. This sequence of deformations is driven by a row of vibrating actuators that vibrate with the same frequency but a phase shift between each consecutive actuator. The metachronal wave arising from this vibration pattern offers efficient locomotion due to the continuous movement of the robot. The top speed achieved in this research was 5 mm/s for both forward and backward locomotion. Our study shows how the robot’s locomotion capabilities are affected by its material and how the robot's velocity depends on the mechanical design and the properties of the metachronal wave and provides a next step into soft robots that can efficiently move almost anywhere.