Bi-Stable Thin Soft Robot for In-Plane Locomotion in Narrow Space
xi wang, Yihan Liu, Junhao TU, Jung-Che Chang, Feiran Wang, Dragos Axinte, Xin Dong
AI summary
Problem
Existing soft robots for narrow-space inspection are often too bulky or rigid, and miniaturizing dielectric elastomer actuators to the millimeter scale while preserving high speed and force remains a significant challenge.
Approach
The authors designed a millimeter-thick actuator that couples a dielectric elastomer with a compliant bi-stable linkage mechanism to amplify displacement and force, using electrostatic adhesive pads for surface anchoring.
Key results
- Achieved 1.1 mm thickness and 1.8 g weight for the Bi-DEA actuator
- Amplified displacement by up to 232% and output force to 630 mN
- Enabled crawling through a 4 mm narrow gap at speeds up to 3.3 mm/s
- Demonstrated reliable crawling and climbing on horizontal and vertical surfaces
Why it matters
This design enables reliable access to millimeter-scale confined spaces for inspection and maintenance in fragile or hazardous environments where conventional robots cannot operate.
Abstract
Dielectric elastomer actuators (DEAs), also recog- nised as artificial muscle, have been widely developed for the soft locomotion robot. With the complaint skeleton and miniaturised dimension, they are well suited for the narrow space inspection. In this work, we propose a novel low profile (1.1 mm) and lightweight (1.8 g) bi-stable in-plane DEA (Bi-DEA) constructed by supporting a dielectric elastomer onto a flat bi-stable mechanism. It has an am- plified 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., letter and acrylic. The thin soft robot has been demonstrated to be capable of crawling through a 4 mm narrow gap with a speed up to 3.3 mm/s (0.07 body length per second and 2.78 body thickness per second).