This paper presents an approach to modeling and simulation of vehicles interacting with the environment (terrain) in a realistic, three-dimensional setting and to assess vehicle mobility based on simulation results. To reliably predict vehicle performance under realistic off-road conditions, lumped-parameter models commonly used in vehicle dynamics are not adequate. In this work, high fidelity, multibody dynamics approach is employed to capture vehicle nonlinear dynamic characteristics. Because all vehicle control forces/moments
are generated at the patch where tire and terrain interacts, tire modeling, soil modeling, and tire-soil interaction modeling are critical. In this work, tire is modeled as multiple-input-multiple-output system with parameters determined via high-fidelity physical-based finite element model and/or test data; soil is modeled using the Bekker-Wong approach with parameters determined using high-fidelity physical-based finite element soil model and/or test data. Although the Bekker-Wong approach is relatively old, effective implementation to achieve its fully potential is possible only recently, with the advent of the so-called dynamic terrain database. A computational algorithm for such an implementation is presented. Dynamic terrain allows natural treatment of the multiple-pass problem in spatial and dynamic fashion, as opposed to the approaches found in the literature that can only deal with planar, steady-state
rolling in an ad hoc fashion. Tire-terrain interaction is modeled using a hybrid approach of empirical and semi-empirical models. A complete simulation environment can be constructed by integrating all the models and mobility analysis of vehicles be perform on soft terrain. An example is presented to demonstrate the approach. Conclusions and future research directions are presented at the end of the paper.