Recent development with respect to localization sensors and more particularly the Global Positioning System (GPS) has permitted to increase significantly the precision of position, up to several centimetres for the real time kinematic GPS (RTK-GPS). Witch such precision, it becomes possible to design devices dedicated to driver assistance for agricultural works. Several systems have been developed to achieve automatically path tracking of frame vehicle using such a sensor. If the final precision of trajectory tracking is satisfying when achieving a straight line on an even ground, for most of these devices it is considerably depreciated when sliding phenomenon appear. As a result, a lateral deviation with respect to the reference path can be recorded, and the precision reached becomes no more satisfying for farmers expectations. Moreover, important delays attached to actuators emphasize such phenomenon and important overshoots are recorded during transient phases. In this paper a global control algorithm is proposed to overcome these problems and to preserve the accuracy of trajectory tracking dedicated to agricultural task. In a first part, an extended kinematic model accounting for sliding effects is presented, as well as the adaptive algorithm, which permits to evaluate sliding effects to feed this model. At first, an extended kinematic model accounting for sliding effects is presented, as well as the adaptive algorithm, which permits to evaluate sliding effects to feed this model. Using this, a control law is designed, which allows compensating sliding effects when conditions are almost constant. A model predictive algorithm relying on path curvature is added to prevent accuracy of fast modifications of sliding conditions, due to a fast modification of curvature. Capabilities of the global control scheme are shown through full-scale experiments using a CLAAS conventional tractor and a Thales aquarius RTK-GPS.
High accurate GPS Guidance for tractors under sliding conditions
Hochgenaue GPS-Führung für Traktoren
2005
8 Seiten, 7 Bilder, 11 Quellen
Aufsatz (Konferenz)
Englisch
TIBKAT | 1967
|SLUB | 1975
|TIBKAT | 2004
|Engineering Index Backfile | 1960
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