Observation of Snails and a Bionic Snail Robot Crawling with Distributed Suction

Slow-speed animals can also exhibit remarkable capabilities, as seen in snails that crawl while maintaining adhesion. Snails have inspired researchers to develop traveling wave-based robots and suction robots; however, the combination of traveling wave propulsion with suction ability remains a challenge. In this paper, we propose a snail-inspired robot that integrates a corkscrew propulsion mechanism with distributed suction cups, enabling it to crawl upside down on the ceiling. The propulsion model of the corkscrew generating the traveling wave is derived, and a temporal-spatial decomposition method is applied to validate the high efficiency of traveling wave generation. The trade-off between wave amplitude and suction cup depth is investigated to determine an optimized configuration. The results show that the robot’s speed aligns well with the propulsion model. The traveling wave ratio calculated from experiments is 0.938. The optimized configuration consists of a corkscrew with a 14 mm diameter and suction cups with a 2.5 mm depth, achieving a crawling speed of 3.02 ± 0.28 mm/s while moving upside down. The combination of the proposed smooth traveling wave generation method and distributed suction cups enables the robot to crawl upside down while carrying a 200 g load and to climb a vertical wall, like a natural snail.