A Rigid Morphing Mechanism Enabled EarthwormLike Crawling Robot

Abstract

Inspired by natural earthworms’ locomotion mechanism, this paper investigates how the earthworm’s muscle works and presents the approach to mimic segmental muscle by employing rigid elementsbased morphing structures. Specifically, the proposed earthwormlike robot employs a class of 2D rigid elements and their array to achieve programable bidirectional 3D deformation, making the formed mechanism precisely controllable and work effectively, thus facilitating the robot’s peristaltic locomotion more efficient. To comprehensively investigate the morphing structure and its formed earthwormlike robot, the kinematics, mechanics, deformationdependent locomotion framework with its adapted model, as well as the factors that affect the optimal velocity are developed and presented. Extensive simulations and experiments on the proposed robot are performed. The results verify the effectiveness of the morphing mechanism and it enabled earthwormlike robot and the consistency between the proposed locomotion model and the practical tests. The results also prove that regardless of the condition of the contact surface, the optimal phase shift angle can be achieved when each segment approximately contracts and relaxes once in one wavelength period. Our developed prototype achieves a speed of multiple body lengths per minute, which is very competitive compared with most developed earthwormlike robots.