Path-Following Control and Terramechanics Analysis for Planetary Rovers Under Wheel-to-Wheel Traction Asymmetry

2026-09-29

AI Summary

This study addresses the slip-induced sinkage and path deviation caused by asymmetric wheel traction in soft terrain. A model-free, purely deceleration-based correction control strategy is proposed, which pioneers heading adjustment through negative slip anchoring of the outer wheels, thereby avoiding the sinkage exacerbation risks inherent in conventional acceleration strategies. Furthermore, it elucidates the terramechanical mechanism by which dynamic load equalization restores thrust capability. Experimental validation using multi-axis force sensing on the EX1 Mars rover platform demonstrates that this strategy effectively suppresses lateral drift at 0.7 m/s without inducing additional sinkage, confirming the practical efficacy of load equalization and thrust recovery.

Abstract

This paper proposes a control strategy for path following that is model-free and relies solely on deceleration for skid-steering planetary rovers navigating deformable loose terrain under continuously imposed traction asymmetry. While conventional controllers that are based on kinematics frequently cause slip-sinkage entrapment by accelerating the wheels during path correction, the proposed approach prevents this failure by setting an upper limit on the maximum commanded velocity. Heading correction is achieved solely through the selective deceleration of the outer wheels, which are located on the outside of the turn, driving them into a negative slip regime to act as a mechanical anchor. The system was evaluated using the four-wheel independent-drive rover EX1 under an asymmetric wheel configuration with different left and right grouser heights that induces significant deviations from the path. Experimental results demonstrate that this deceleration-only control successfully suppresses accumulated lateral drift across various velocity regimes up to 0.7 m/s without causing sinkage. Crucially, direct force measurements from onboard multi-axis sensors provide important empirical evidence of the underlying terramechanics, proving that the targeted deceleration establishes dynamic load equalization across the chassis and completely restores the native thrust capability of the opposite driving wheel.

Problem

• path-following control
• planetary rovers
• traction asymmetry
• slip-sinkage entrapment
• terramechanics

Innovation

• Path-following control
• Skid-steering rover
• Deceleration-only strategy
• Terramechanics
• Traction asymmetry