Automatic guidance of an off-road mobile robot with a trailer Application to the control of agricultural passive towed implements

However, new functionalities may be required to provide more effective farm work. In fact, passive towed implements, attached at one hitch point on a drawbar at the rear of the tractor, perform the agricultural task in the field, but several effects as ground conditions, curves and slopes may force them to shift away from the tractor's path, leading to unsatisfactory implement position and inaccurate agricultural work, see (Kormann and Thacher, 2008) and the illustrations in Fig. 1. The trend toward increasingly heavy and long implements accentuates this problem. Moreover, instead of performing large loop turns in headland with a vehicle-trailer combination, it would be sometimes interesting to be able to perform reverse turns, executed with two stop points and a backward motion, see Fig. 2, in order to reduce the required area width for turning on the adjacent track. In all these situations, the ability to guide the tractor in such a manner that the passive towed implement would be accurately stabilized on the track to follow, is therefore required.