Unifying Sidewinding and Rolling: A Wave-Based Framework for Self-Righting in Elongated Limbless and Multi-Legged Robots

2026-03-08

AI Summary

This study addresses the challenge of self-righting in slender multi-legged robots, which are prone to overturning during obstacle negotiation and lack a generalizable strategy adaptable to varying leg numbers and lengths. By integrating biomimetic comparative analysis, a tunable-leg-length robotic platform, and systematic experimentation, the authors propose a unified control framework based on undulatory motion. Their findings reveal a critical coupling between leg length and self-righting capability, identifying a threshold leg length: short-legged robots can achieve robust self-righting using ground reaction forces, whereas long-legged robots must rely on aerial reorientation. The work further establishes a morphology–strategy co-design principle, offering theoretical insight and practical guidance for the joint optimization of structure and control in multi-legged robots operating in complex terrains.

Technology Category

• Intelligent Robots: Multi-Robot Systems
• Multiagent Systems: Multiagent Systems under Uncertainty
• Natural Language Processing: Safety and Robustness

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Search and Retrieval-Augmented AI: Multilingual and cross-lingual Web search
• Web Mining and Content Analysis: Robustness and generalizability of Web mining methods

Abstract

Centipede-like robots offer unique locomotion advantages due to their small cross-sectional area for accessing confined spaces, and their redundant legs enhance robustness in cluttered environments such as search-and-rescue and pipe inspection. However, elongated robots are particularly vulnerable to tipping over when climbing large obstacles, making reliable self-righting essential for field deployment. Self-righting strategies for elongate, multi-legged systems remain poorly understood. In this study, we conduct a comparative biomechanics and robophysical investigation to address three key questions: (1) What self-righting strategies are effective for elongate, many-legged systems? (2) How should these strategies depend on morphological parameters such as leg length and leg number? (3) Is there a morphological limit beyond which reliable self-righting becomes infeasible? We compare two biological exemplars: Scolopendra subspinipes (short legs) and Scutigera coleoptrata (house centipedes with long legs). Scolopendra subspinipes reliably self-rights both during aerial phases and through ground-assisted self-righting, whereas house centipedes rely predominantly on aerial reorientation and struggle to generate effective self-righting torques during ground contact. Motivated by these observations, we construct a parameterized space of bio-inspired self-righting strategies and develop an elongate robot with adjustable leg lengths. Systematic experiments reveal that increasing leg length necessitates a shift in control strategy to prevent torque over-concentration in mid-body actuators, and we identify a critical limb-length threshold above which robust self-righting becomes challenging. These results establish morphology-strategy coupling principles for self-righting in elongate robots and provide design guidelines for centipede-like systems operating in uncertain terrain.

Problem

• self-righting
• elongated robots
• multi-legged locomotion
• morphological parameters
• centipede-inspired robotics

Innovation

• self-righting
• morphology-strategy coupling
• bio-inspired robotics
• centipede-like robots
• wave-based locomotion