A Novel Paddling Propulsion Gait for a Wheel-Legged Robot on Sand Terrain

Abstract

Autonomous Mobile Robots are typically limited to structured environments, as conventional wheeled propulsion often fails on deformable terrains like sand due to excessive wheel slip and sinkage. To address this mobility challenge, this paper introduces a novel locomotion strategy for a high-degree-of-freedom wheel-legged robot. The proposed method is a gait based on an asymmetric "dynamic compact-and-push" cycle, where the robot's limbs perform a paddling-like motion to actively remodel the granular media. This active terrain remodeling allows the robot to generate net forward thrust where conventional wheeled locomotion is ineffective. We systematically designed and experimentally validated four distinct gaits founded on this principle. The results demonstrate that this approach enables sustained forward motion in an environment where wheeled propulsion is verified to fail, with the asynchronous paddling gait proving most effective. This work contributes a new, validated locomotion mechanism for sand terrains and provides a quantitative comparison of different limb coordination strategies.