Mechanical model and experimental investigation of a novel pneumatic foot

Abstract

Almost all forms of soft crawling robots and animals rely on frictional anisotropy to achieve terrestrial locomotion. However, the electroadhesion force of actuators is limited to the materials, roughness of various terrain, and patterning high- and low- friction materials on the ventral side of the robot can only enable the robot to crawl along a single direction. This paper presents a novel pneumatic foot that can regulate the friction between itself and the crawling surface to achieve frictional anisotropy in two opposite directions. The design scheme, working mechanism and analytical model based on the energy method of the pneumatic foot are described. The accuracy of the analytical model is verified by numerical simulation and experimental study. A soft crawling robot, including its locomotion mode and control system, is designed. Crawling experiments on various terrain and payload experiments are conducted to prove the feasibility of the pneumatic foot. The pneumatic foot can enable the robot to crawl on various terrain at a maximum speed of 0.128 BL/s. When the payloads are 4.29 times of the robot’s weight, the crawling speed is still relatively high (0.108 BL/s). This pneumatic foot can be applied to biomimetic inchworm or earthworm robots on various terrain and in some limited space, such as the air ducts of central air-conditioning.