Carrier-Phase Differential GPS for Control of a Tractor Towed Implement

David M. Bevly and Bradford Parkinson

Abstract:	This paper explores the use of GPS position measurements on a tractor towed implement for position control of the implement. Several recent papers have focused on automatic steering control of farm vehicles using GPS. This paper extends that work to control a towed implement through automatic steering of a farm tractor. Many times implements are driven on curved trajectories, side-hills, or contours where the implement and tractor positions may differ. Additionally, some heavy implements will "pull heavy" to one side, creating a position bias. It would be advantageous to be able to control the actual position of the implement as opposed to the position of the tractor in these various circumstances. A simple analytical model is developed for the tractor/implement combination. The model is validated with experimental data using Carrier Phase Differential GPS position on the tractor as well as on the implement. A controller is then designed and implemented on the experimental system to control the position of the implement on a given path across the field. Experimental data is given to show the ability to control the position of the implement to within 10 cm of the desired path.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	2263 - 2268
Cite this article:	Bevly, David M., Parkinson, Bradford, "Carrier-Phase Differential GPS for Control of a Tractor Towed Implement," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 2263-2268.
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