Correction of GPS Positioning by Vehicle Inclinations for Agricultural Vehicle Guidance

Abstract

A GPS is widely used as a positioning system for an automatic vehicle guidance. But, generally a GPS antenna is installed at the top of a vehicle whose height is 2 to 3 meters from the ground, a position error raised from vehicle inclinations (roll and pitch) is included. In this research, to increase travel accuracy of vehicle guidance, we propose the correction method of the position error caused by vehicle inclinations. To evaluate a performance of the developed correction method, the travel test by giving roll and pitch was conducted. The average of lateral error indicated about 17.1cm, when the vehicle traveled without inclination correction, while the average error was reduced up to about 2.1cm by introducing the inclination correction. In addition, to investigate the performance under higher velocity, the traveling test in which running speed exceeding 4.0m/s was also carried out. Without the inclination correction, the R. M. S. error in the lateral direction of the vehicle reached 10.4cm. On the other hand, when the developed correction method was utilized, the R. M. S. error decreased to about 3.8cm. It was concluded that the performance of the developed guidance system on high speed travel was satisfied with actual field managements.