Comprehensive pressure-sinkage model for small-wheeled unmanned ground vehicles on dilative, deformable terrain

This paper details a novel pressure-sinkage model for small-diameter, rigid wheels on dilative soils. Pressure-sinkage models are fundamental to the prediction of UGV mobility on deformable terrains. The proposed model builds on previous work in which the flat-plate pressure-sinkage assumption of classical terramechanics was shown to yield diminished accuracy for UGVs with wheels less than 50 cm in diameter. It has been shown that classical pressure-sinkage models can be modified by a diameter dependent term, yielding greatly increased accuracy. Here, an investigation into the effect of wheel width on the diameter-dependent model is detailed. Results from over 250 pressure-sinkage tests on three soils using 85 wheel geometries are summarized. The results of this investigation are used to create a comprehensive pressure-sinkage model for dilative soils that includes wheel width and diameter parameters. The physics of the model are visually validated with X-ray images of sub-surface soil deformation during the wheel indentation process. A comparison between the dilative soil pressure-sinkage model and a previously obtained model for compactive soils is also presented. The pressure-sinkage model presented here can be used to improve the accuracy of the terramechanics framework and UGV mobility predictions.