A modified pressure–sinkage model for small, rigid wheels on deformable terrains

Bekker’s semi-empirically derived equations allow the designers of off-road vehicles to understand and predict vehicle mobility performance over deformable terrains. However, there are several underlying assumptions that prevent Bekker theory from being successfully applied to small vehicles. Specifically, Bekker’s sinkage and compaction resistance equations are inaccurate for vehicles with wheel diameters less than approximately 50 cm and normal loading less than approximately 45 N. This paper presents a modified pressure–sinkage model that is shown to reduce sinkage and compaction resistance model errors significantly. The modification is validated with results from 160 experiments using five wheel diameters and three soil types.