Implement lateral position accuracy under RTK-GPS tractor guidance

The accuracy of global positioning system receivers can be improved by differential correction systems (DGPS), which deliver sub-meter accuracy. Higher-accuracy, of about 1 cm on-the-go, is delivered by units generally referred to as real-time kinematic (RTK) DGPS systems. RTK-DGPS systems are presently used by commercial companies for automatic guidance of tractors in row-crop operations. Since high-end DGPS systems with high-accuracy are generally very expensive, it is necessary that the commercial benefit be maximized and that any related errors will be minimized. In the present study, the deviations from a predetermined route of a three-point hitch implement mounted on a RTK-DGPS based automatically guided tractor were recorded and were used to validate that the implement deviation is strongly dependent on the distance from the tractor rear axle. The recorded deviations were analyzed for paved and rough surfaces; the latter caused substantially greater deviations. Based on the above hypothesis, a possible way to improve the performance by reducing the deviations at a point on the implement is suggested.