Measurement of rover wheel-soil interaction parameters using piezoresistive pressure matrix sensors

Rovers for planetary exploration often face mobility challenges due to the interaction between their motion systems and the extraterrestrial soils. These challenges, mainly related to the geometry of the wheel and the mechanical characteristics of the soil, include high slip ratio, excessive sinkage, and potential entrapment. Accurate characterization of the wheel–soil interaction is therefore essential to prevent early damages, thus optimizing the potential operative life. In recent years, various methods have been proposed to measure wheel–soil stress. This study introduces a novel experimental approach for measuring the two-dimensional pressure distribution beneath a wheel, employing a pressure matrix sensors embedded within granular soil. This system allows the direct measurement of the contact pressure during wheel passage and the estimation of key interaction parameters such as wheel–soil contact angles. The paper details the experimental setup used for both static and dynamic tests, the data processing methodology and the main results interpretation. Experimental findings demonstrated the effectiveness of the proposed method to capture the two-dimensional wheel–soil stress distribution and to provide a reliable estimation of the contact angles. Comparison with terramechanics models showed good agreement, highlighting the method potential for model validation and for enhancing the understanding of soil–wheel interaction dynamics. Additionally, the results allowed the introduction of a stress attenuation ratio , defined as the ratio between the theoretical and the experimental maximum pressures, calculated at a certain depth below the contact zone.