Earthworm‐Inspired Soft Robot Design Based on Non‐Uniform Poisson's Ratio Structure

ABSTRACT The mechanism by which earthworms achieve efficient peristaltic locomotion, characterized by the coordinated thinning/lengthening and thickening/shortening of their body segments, has long been a classic subject of study in biomimetic robots. Inspired by earthworm peristalsis, this study proposes a cylindrical soft robot with a non‐uniform Poisson's ratio. Its negative and positive Poisson's ratio regions mimic the anchoring function of the earthworm's longitudinal muscles and the propulsive extension function of circular muscles, respectively. A single‐motor‐driven two‐regions robot was first developed, achieving forward locomotion in horizontal pipes, but a momentary loss of wall contact prevented vertical climbing. To overcome this, a four‐region robot was designed. Applying a quarter‐cycle phase difference between two serially connected units ensures continuous wall contact. This enhances horizontal speed and stability and, via waveform optimization, enables anti‐gravity climbing in vertical pipes. The robot also adapts to different pipe diameters by adjusting driving parameters, demonstrating good environmental adaptability. This work provides a novel, simple, and controllable solution for soft robots, demonstrating broad application prospects in the field of pipeline inspection.