Morphing MILR: Design and control of a cable-driven limbless robot with rolling joints for maneuvering in complex environments

2026-07-21

AI Summary

This work addresses the challenge that limbless robots often struggle to simultaneously achieve robust compliance-driven actuation and multimodal locomotion adaptability. To overcome this, the authors propose a novel cable-driven architecture integrating programmable passive compliance, rolling joints with gear-based locking, and a distributed actuation mechanism. This design uniquely unifies reconfigurable bending compliance, rolling degrees of freedom, and self-locking shape retention within a single platform, enabling dynamic reconfiguration of body morphology and bending planes without continuous energy input. Even in the absence of high-bandwidth feedback, the system reliably executes diverse locomotion modes—including lateral undulation, sidewinding, rolling, and twisting—and demonstrates seamless gait transitions and robust traversal through densely cluttered environments, significantly enhancing the mobility and environmental adaptability of limbless robots in complex scenarios.

Abstract

Limbless robots offer exceptional mobility in confined and cluttered environments due to their slender bodies and their ability to exploit body-terrain interactions. Recent designs incorporating compliance demonstrate robust locomotion without complex sensing or control; however, these systems typically rely on fixed body configurations, with each morphology specialized for a single locomotion mode or environment. This raises a key challenge: how can a single limbless robot achieve versatile locomotion while preserving the robustness of compliance-mediated locomotion? To address this challenge, we present a cable-driven limbless robot that reconfigures body morphology and compliance to enable diverse locomotion modes. Distributed cable actuation generates traveling body waves, while programmable passive compliance enables robust contact-rich locomotion without terrain knowledge or high-bandwidth feedback. Rolling joints reorient bending planes along the body, enabling rapid reconfiguration and smooth transitions between locomotion styles, and incorporate geared locking to maintain configuration without continuous power. By combining programmable bending compliance and morphology control, the platform achieves lateral undulation, sidewinding, rolling, and twisting within a single system. Experiments demonstrate reliable gait generation, traversal in obstacle-rich environments, and transitions between modes, establishing a versatile limbless platform for navigating complex environments with applications in search and rescue, environmental monitoring, and inspection.

Problem

• limbless robot
• versatile locomotion
• compliance-mediated locomotion
• morphology reconfiguration
• complex environments

Innovation

• morphing
• cable-driven
• programmable compliance
• rolling joints
• limbless robot