A Crawling and Rolling Soft Robot With an Interlocking Design

In recent years, the field of soft robotics has gained considerable attention, due to the high versatility of soft robots in adapting their flexible bodies to unknown environments, resulting in the development of a wide range of robots. Inspired by the morphology and locomotion mechanisms of inchworms and earthworms, various worm-like soft robots have been proposed, typically utilizing a single mode of locomotion such as crawling. In this paper, a worm-like pneumatic soft robot with an interlocking design that realizes bidirectional rolling on flat surfaces and bidirectional crawling on flat platforms and within a pipe, is presented. The crawling locomotion is inspired by the two-anchor crawling observed in biological species, where the animal alternately anchors its rear and front ends as its body elongates or shrinks. The robot consists of two multi-chamber radial actuators encapsulated in plastic cage frames and an axial actuator housed between the interlocking parts. The inflation of one of the radial actuators results in anchorage of the robot on that side, allowing the body to move when the central axial actuator is engaged. Sequential actuation of the individual chambers, near the dead ends on both sides, allows the robot to roll. A prototype of the robot was developed and tested. The results confirmed the robot’s ability to crawl bidirectionally at approximately 16 cm/min on flat surfaces, 15 cm/min inside pipes, and roll up to 40 cm/min on flat surfaces. The transition between these modes was achieved through usage of different patterns, without any hardware modifications.