Legless Crawling Robot That Moves by Inflating and Shrinking Elastic Sheets with Extension and Contraction of Bodies That are Driven by Twisting Motion

Abstract

Crawling is a useful method to move in narrow environments such as tubes or tunnels. Many crawling robots have been investigated that mimics peristalsis by inflating/shrinking thin elastic film while extending/contracting connected bodies. However, elastic film-based actuation is vulnerable under harsh environments such as having rugged surface, under thin air, or being exposed at high temperature. In addition, inflation by air pressure requires a large air pump, which prohibits autonomy of a robot. In this research, we propose a crawling mechanism that uses hard thin elastic metal or plastic plates as inflators, which are driven by only a simultaneous twisting and extending motion performed by adjacent bodies. We propose a design of two types of units that inflate or shrink according to body twisting extension motion. By connecting these units, and by providing appropriate extension/contraction sequence, it is shown that the connected units perform crawling motion like peristalsis. This paper shows the design of two types of units and the sequence to realize crawling motion, with the results by a prototype robot.