An analysis of the Yutu lunar rover’s mobility performance using a multibody dynamics framework and a physics-based terramechanics model

The interaction between wheels and soil has a significant impact on the dynamics of extraterrestrial vehicles in terrame-chanics applications. With very few exceptions, the mobility analysis of extraterrestrial rovers has been carried out using empirical terramechanics models originally established for military vehicle mobility analysis. This contribution employs a physics-based terramechanics model, the so called continuum representation model (CRM), which employs partial differential equations solved using the smoothed particle hydrodynamics (SPH) method. The resulting terramechanics model displays the speed of the simpler empirical models, yet produces results comparable in fidelity to those generated by the computationally costly discrete element method (DEM). We demonstrate the versatility of the CRM approach by simulating the single-wheel system of the Yutu lunar rover. Simulations were conducted to comparatively analyze the effects of particle size, slip control policy, and soil parameters on wheel performance. The accuracy of the single-wheel CRM results was assessed using “ground truth” DEM results. Subsequently, to gain a system-level understanding of the performance of the Yutu rover, the vehicle was modeled as a multibody system, and mobility simulations were run on de-formable CRM terrain. The performance of the full rover, as captured in tractive force, wheel torque, wheel sinkage, and traction vs. slope tests, was examined under various test conditions. Finally, we examine how various wheel features, e.g., its radius and grouser width/height/count, affect the mobility performance of the rover. All simulations were conducted using an open-source, publicly available simulator called Chrono. The scripts and models used to generate the results presented in this paper are available upon request to support reproducibility studies and further research.