Ultrasonic Sensor Development for Automatic Steering Control of Orchard Tractor

This paper describes the measurement of the relative position between tree canopy and vehicleusing ultrasonic sensors for the navigation of a tractor working in the orchard. The tractorworking in the orchard travels on the permanent paths between trees. Therefore, the navigationof the tractor using a DGPS seems to be effective. However, since the trees grow up and changethe dimension of tree canopies, the tractor needs to detect the tree canopies and travel alongthem or avoid them. The goal of this research is to navigate the orchard tractor using a DGPSand ultrasonic sensors. For the purpose, the ultrasonic instrument for the measurement of thetree canopy was developed in this research. The performance of the developed ultrasonicinstrument was estimated by field tests. Furthermore, a DGPS was used for the measurement ofthe vehicle position. The performance of the DGPS was also presented.