A Novel Paddling Propulsion Gait for a Wheel-Legged Robot on Sand Terrain
En-Chieh Tsui, Wei-Ting Chen, Wei-Shun Yu, Hung-Hsin Chen, Shaoyu Chien, Pei-Chun Lin
AI summary
Problem
Conventional wheeled robots suffer from excessive slip and sinkage on deformable terrains like sand, often leading to complete immobilization. This paper addresses how to achieve reliable, sustained propulsion in such environments where traditional traction mechanisms fail.
Approach
The robot executes an asymmetric dynamic compact-and-push paddling gait, using its articulated limbs to laterally displace and compact loose sand before pushing against the newly densified ground to generate forward thrust.
Key results
- Validated four distinct paddling gaits through physical experiments on a granular testbed
- Asynchronous paddling gait achieved the highest forward displacement and best overall performance
- Confirmed conventional wheeled mode fails on sand with slip ratios exceeding 84%
- Provided quantitative comparison of propulsive effectiveness and energy efficiency across gait variations
Why it matters
Enables reliable robot mobility in unstructured, deformable environments critical for planetary exploration, agriculture, and search-and-rescue operations.
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.