Bi-stable thin soft robot for in-plane locomotion in narrow space

TL;DR

This paper introduces a novel bi-stable dielectric elastomer actuator integrated into a thin soft robot, enabling effective in-plane locomotion in narrow spaces with enhanced force and displacement capabilities.

Contribution

The work presents a low-profile, lightweight bi-stable DEA design and demonstrates its application in a soft robot capable of crawling through 4mm gaps.

Findings

Enhanced displacement and force output of the Bi-DEA compared to traditional in-plane DEAs.

Successful crawling and climbing in narrow gaps as small as 4mm.

Robot achieves a crawling speed of 3.3mm/s in narrow spaces.

Abstract

Dielectric elastomer actuators (DEAs), also recognized as artificial muscle, have been widely developed for the soft locomotion robot. With the complaint skeleton and miniaturized dimension, they are well suited for the narrow space inspection. In this work, we propose a novel low profile (1.1mm) and lightweight (1.8g) bi-stable in-plane DEA (Bi-DEA) constructed by supporting a dielectric elastomer onto a flat bi-stable mechanism. It has an amplified displacement and output force compared with the in-plane DEA (I-DEA) without the bi-stable mechanism. Then, the Bi-DEA is applied to a thin soft robot, using three electrostatic adhesive pads (EA-Pads) as anchoring elements. This robot is capable of crawling and climbing to access millimetre-scale narrow gaps. A theoretical model of the bi-stable mechanism and the DEA are presented. The enhanced performance of the Bi-DEA induced by the mechanism is experimentally validated. EA-Pad provides the adhesion between the actuator and the locomotion substrate, allowing crawling and climbing on various surfaces, i.e., paper and acrylic. The thin soft robot has been demonstrated to be capable of crawling through a 4mm narrow gap with a speed up to 3.3mm/s (0.07 body length per second and 2.78 body thickness per second).