An approach of identifying mechanical parameters for lunar soil based on integrated wheel-soil interaction terramechanics model of rovers

The research of lunar soils' mechanical property parameters can both improve our scientific knowledge of the moon's geological properties, and provide engineering knowledge required for development of exploration rovers or future human settlement activities. Experiments are carried out for six kinds of wheels with different dimensions and wheel lugs using the wheel-terrain interaction test-bed developed for lunar rovers and lunar soil stimulant, the mechanical property parameters of which are measured by conventional plate-sinkage experiments and shearing experiments. The degree of coupling and parameter sensitivity are analyzed for the integrated wheel-soil interaction terramechanics model, based on which the eight mechanical parameters are divided into three groups, i.e., contact angle coefficients, bearing performance parameters and shearing performance parameters. A cyclic iterative parameter identification approach is brought forward to estimate the three groups of parameters step by step, using the measured data that have maximum correlativity with them respectively, i.e., drawbar pull, wheel sinkage, and resistance moment. The experimental data are adopted to verify the approach, it is proved that three of the shearing parameters of soil can be identified with high precision; the lumped sinkage modulus can be set to a typical value; the sinkage exponent coefficients and contact angle coefficients are correlated to the wheel, reflecting the effects of wheel dimensions and lugs. The parameter identification error caused by the simplified models is decreased effectively, and mechanical parameters of the lunar soil can be identified comprehensively. This approach can be used for estimating soil property and it can improve prediction precision of wheel-soil interaction mechanics model.