New perspective on characterizing pressure–sinkage relationship of terrains for estimating interaction mechanics

• New concept of modelling terrains’ bearing performance with variant sinkage exponent.
• Characterizing the pressure-sinkage relationship of terrains with two parameters.
• Intrinsic stiffness modulus with constant dimension of Pa/m has dominant role.
• Variant sinkage exponent can be identified to reflect multiple influential effects.
• Dynamic sinkage, dimension effect and load are reflected and verified by experiments.

Conventional pressure–sinkage models of characterizing bearing properties of terrains for vehicles are semi-empirical with poor adaptability and extrapolation ability; definitions of parameters are nonintuitive. The purpose of this paper is to provide more general and high-fidelity models for terrain characterization to satisfy the high requirements of autonomous wheeled vehicles, which should “understand” terramechanics in an accurate way on off-road terrains. Based on the analysis of conventional models and experimental results, new perspective and related equations on characterizing bearing performance are proposed. The stiffness modulus which is an intrinsic terrain parameter with determined unit of Pa/m has dominant role in governing the bearing performance. The sinkage exponent is variable as the function of various influential factors. Numerical analysis verifies that the new model with two meaningful parameters has high goodness of fit with Bekker’s model. Experimental results verifies that the new model using constant stiffness modulus and variable sinkage exponent reflects key factors such as dynamic sinkage, dimension effect, payload effect, and lug effect with high fidelity, which are not considered by the conventional models. This concept could be applied to various terrains and conventional vehicles.