Enabling High-Curvature Navigation in Eversion Robots through Buckle-Inducing Constrictive Bands

2026-01-18

AI Summary

This study addresses the limited navigability of inverted robots in high-curvature, confined channels by proposing a passive buckling modulation mechanism that eliminates the need for artificial muscles or active steering components. By periodically integrating inextensible constriction bands along the robot’s outer wall, localized buckling is induced to reduce bending stiffness, enabling compliant and reliable navigation through tight curves. Leveraging Cosserat rod theory, the authors model the resulting local stiffness variations and validate the design through structural analysis and experiments. The developed robot achieves up to a 91% reduction in tip bending stiffness, successfully traversing a 180° bend with a radius as small as 25 mm—significantly outperforming conventional designs limited to 35 mm—and demonstrates clinical feasibility in a colon phantom model.

Technology Category

• Intelligent Robots: Manipulation
• Natural Language Processing: Safety and Robustness
• Computer Vision: Vision for Robotics & Autonomous Driving

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

Tip-growing eversion robots are renowned for their ability to access remote spaces through narrow passages. However, achieving reliable navigation remains a significant challenge. Existing solutions often rely on artificial muscles integrated into the robot body or active tip-steering mechanisms. While effective, these additions introduce structural complexity and compromise the defining advantages of eversion robots: their inherent softness and compliance. In this paper, we propose a passive approach to reduce bending stiffness by purposefully introducing buckling points along the robot's outer wall. We achieve this by integrating inextensible diameter-reducing circumferential bands at regular intervals along the robot body facilitating forward motion through tortuous, obstacle cluttered paths. Rather than relying on active steering, our approach leverages the robot's natural interaction with the environment, allowing for smooth, compliant navigation. We present a Cosserat rod-based mathematical model to quantify this behavior, capturing the local stiffness reductions caused by the constricting bands and their impact on global bending mechanics. Experimental results demonstrate that these bands reduce the robot's stiffness when bent at the tip by up to 91 percent, enabling consistent traversal of 180 degree bends with a bending radius of as low as 25 mm-notably lower than the 35 mm achievable by standard eversion robots under identical conditions. The feasibility of the proposed method is further demonstrated through a case study in a colon phantom. By significantly improving maneuverability without sacrificing softness or increasing mechanical complexity, this approach expands the applicability of eversion robots in highly curved pathways, whether in relation to pipe inspection or medical procedures such as colonoscopy.

Problem

• eversion robots
• high-curvature navigation
• bending stiffness
• soft robotics
• compliant locomotion

Innovation

• eversion robot
• buckling
• constrictive bands
• passive steering
• soft robotics