Prediction of Tractive Limitations of a Rigid Wheel on Loose Soil

Abstract

Predicting the tractive limitations of locomotion gears is of critical importance in a robotic vehicle system on natural terrain. In particular, it is imperative for an unmanned mobile robot to avoid getting stuck in loose soil to retain its mobility. From this perspective, this paper attempts to theoretically predict the limitations of a typical wheel in such loose soil based on traditional soil-wheel interaction models. In the case that the model brings a negative drawbar pull exerted by the wheel under any kinematic slip condition, we analytically investigated the limitations using a ratio of sinkage over the wheel radius. Predicted limitations are suggested for design optimization and control of the wheeled vehicle. Furthermore, this paper presents the relationship between the model analysis and a practical single wheel test, which provides significant guidelines for usage of the experimental results.