In the near future, off-road mobile robots will feature high levels of autonomy which will render them useful for a variety of tasks on Earth and other planets. Many terrestrial applications have a special demand for robots to possess similar qualities to human-driven machines: high speed and maneuverability. Meeting these requirements in the design of autonomous robots is a very hard problem, partially due to the difficulty of characterizing the natural terrain that the vehicle will encounter and estimating the effect of these interactions on the vehicle. Here we present a dynamic traction model that describes vehicle braking on a variety of terrestrial soil types and in a wide range of natural landscapes and vehicle velocities. This model was developed empirically, it is simple yet accurate and can be readily used to improve model-predictive planning and control. The model encapsulates the specifics of wheel-terrain interaction, offers a good compromise between accuracy and real-time computational efficiency, and allows straight-forward consideration of vehicle dynamics.
