Path following control of an off-road track vehicle towing a steerable driven implement

In this paper, nonlinear controllers are designed for an accurate path-following of a track vehicle towing an active implement, which is steered and driven, in off-road terrains like farms where longitudinal and lateral slips at front tracks and rear steerable wheels are inevitable. These controllers are based on path offset values and a partial dynamic model. The controller is designed to minimize the lon-gitudinal force at the hitch point and steer the track vehicle and the implement´s wheels for an accurate path-following. Error vectors are introduced to combine the measured longitudinal force at the hitch point and the path offset values for both the track vehicle and the implement. Afterwards, two pairs of virtual states are introduced and nonlinear contracting sliding mode controllers are designed to control the error values. The two cases of the track vehicle without the implement control and the track vehicle with the implement control are compared using dynamic simulations. The results show improvements in the path-following accuracy and the drivability of the whole system when the track vehicle control and the steering and drive force controller of the implement is enabled on simulated off-road terrains.