Design of an Inchworm-Inspired Crawling Robot Based on Dielectric Elastomers

Soft crawling robots offer significant advantages in environmental adaptability and safe interaction; however, most existing systems rely on rigid-flexible hybrid structures or adsorption mechanisms, which limit stable bidirectional locomotion under fully flexible conditions. This study proposes a completely soft forward-backward crawling robot (OA-FBCR) composed of acute-angled and obtuse-angled dielectric elastomer minimum energy structure (DEMES) units. The robot achieves bidirectional motion solely through the electro-induced deformation of dielectric elastomers, without requiring rigid frames, mechanical joints, or electrostatic adsorption. An electromechanical coupling model combined with finite element analysis is developed to elucidate the relationship between structural geometric parameters and driving performance. The results demonstrate that a "top-aligned" configuration significantly enhances bending capability, with a maximum bending angle of up to 140°.Experimental investigations further reveal that the pre-stretch ratio and the hollowed-area geometry strongly influence actuation performance. Using an optimized gait control strategy, the robot achieves stable and repeatable forward and backward locomotion at approximately 5 mm/s across various terrains, while the speed increases to 8 mm/s on a 40° slope. This work provides a new technical pathway for fully soft bidirectional crawling robots and micro-scale flexible exploration devices.