Evaluation of the accuracy of an auto-navigation system for a tractor in mountain areas

Tractors are mostly utilized in the field for agriculture. And the driving of tractors is a hard and boring job. In order to reduce the labor force for driving tractors and improve the working efficiency. An auto-navigation system was developed using global positioning system (GPS). The auto-navigation system are mostly researched in the flat fields, but in Japan more than 70% of the fields are located in the mountain area. The auto navigation accuracy for the tractors is reported can be as high as 0.05 m in the flat field. However, what about the accuracy and how it is influenced in the mountain areas have not been clarified. In this study, the influence to the auto navigation system for the tractor will be studied by running a tractor using an auto-navigation system, and the width between the neighbor paths after-running were manually measured, and using a high precision real time kinematic GPS (RTK-GPS) and an inertial measurement unit (IMU). The IMU was utilized to measure the inclination of the sloped field. The field experiment results show that the error is about ±0.1 m in the experiment field when the roll angle is about 4 deg. And the error is directly influenced by the roll angle.