Design of a soft crawling robot based on Kresling origami structure

Abstract This paper presents a soft pipeline robot based on a Kresling -inspired origami structure, integrating an axially extensible structure with variable-friction anchoring feet to achieve coordinated crawling, anchoring, and steering in confined environments. To characterize the robot’s fundamental mechanics, a mathematical model based on spatial geometric constraints was first established to describe the relationships among the relative rotation angle, axial height, and folding ratio. Subsequently, an energy evolution model incorporating crease strain energy analysis was developed to derive the optimal parameter ranges for rapid folding and deployment. A comprehensive dynamic model of the entire robot was then developed by integrating pneumatic actuation with a differential friction mechanism. By accounting for the axial driving force, anchoring force, and frictional resistance, this model elucidates the mechanisms governing rapid response and stable crawling under pneumatic excitation. Furthermore, theoretical predictions regarding the folding ratio, the relationship between pressure and driving force, anchoring force, and single-cycle displacement were validated through rigorous comparison with experimental measurements. Comprehensive performance evaluations were conducted, including fundamental metrics such as folding ratio, driving force, response speed, and anchoring force, as well as crawling and steering experiments in pipelines with varying diameters and curvatures. The results demonstrate that the robot exhibits a high folding ratio, substantial axial output force, and rapid dynamic response. By combining these capabilities with the friction feet mechanism, the robot achieves efficient locomotion and steering, thereby addressing the challenge of balancing operational efficiency and flexibility in complex pipeline environments. Consequently, the proposed robot demonstrates significant potential for exploration and inspection tasks in confined spaces.