A high load capacity and efficient-transporting inchworm-like crawling robot with bistable structure and pneumatic networks actuator

Abstract Although pneumatic soft crawling robots have made great progress, there are still several difficulties hindering their practical progress, the most important of which is the insufficient stiffness and the insufficient load capacity under large deformations. An inchworm-like soft crawling robot with load capacity and deformability is proposed in this paper. Bistable composite structures are typically smart morphing variable stiffness structures with lightweight, good stiffness under large deformations and possessing two stable configurations. Instead of traditional materials with high Young’s modular, the inchworm-like crawling robot, which consists of a stiffness-enhancing hybrid actuator integrating a bistable shell with a soft pneumatic actuator for the main body and two bristle structures for the feet, has lightweight, flexibility, and high stiffness under large deformations. By controlling the stiffness-enhanced hybrid actuator, the robot is capable of achieving crawling and reversing motions like an inchworm. Experimental results show that the tip output force of the inchworm-like deformed trunk was five times larger than a single pneumatic actuator, which means that the inchworm-like robot owns excellent driving performance and flexibility. The collapse of an inchworm-like deformed trunk with 100 g load is less than the collapse of a single pneumatic networks actuator. This also demonstrates that the bistable structure exactly improves the load capacity of the crawling robot. The periodic bending-flattening motion of the actuator is transformed into the unidirectional crawling motion of the robot by installing feet on both sides of the actuator. The crawling robot also can perform well in environments with different angles, heights, and surfaces, which is verified by experiments. The inchworm-like crawling robot provides a method to improve the load capacity while maintaining the flexibility of soft robots and demonstrating huge practicability in field exploration and goods transportation.