Mobile robot control in presence of sliding: Application to agricultural vehicle path tracking

Control design of mobile robots dedicated to path tracking tasks is generally based on the rolling without sliding assumption at the wheel/ground contact point. However, such an hypothesis is not relevant for off-road vehicle and the use of non sliding assumption in this case leads to important tracking errors. Moreover, the vehicles considered for off-road applications (such as agricultural tasks) have generally important mass and inertia and are equipped with low reactive actuators. As a result, delays are introduced into the control loop, which depreciate considerably the performances of autonomous path tracking, especially during a modification of path curvature. This paper proposes several developments, relying on adaptive and predictive observer-based control, dedicated to automatic guidance of off-road mobile robots. The relevancy of the proposed algorithm is investigated via full scale experiments, carried out with a farm tractor, as the considered application is agricultural work