A DYNAMIC PATH SEARCH ALGORITHM FOR TRACTOR AUTOMATIC NAVIGATION

Abstract

This article presents the development of a dynamic path search algorithm for an intelligent navigator used to guidean autonomous agricultural tractor to track the desired path and make turns at the end of field. This dynamic path search algorithmuses posture sensors to determine the current tractor position and a tractor dynamics model to estimate the future tractorposition. The posture sensors include a real-time kinematic global positioning system (RTK-GPS) receiver and a fiber-opticgyroscope (FOG). The outputs from the dynamic path search algorithm are tractor lateral deviation and the desired yaw angle.Based on these outputs, an intelligent navigator will create appropriate steering angles to guide the tractor along the desiredpath. The developed dynamic path search algorithm was first evaluated in computer simulation and then validated via field tests.The path tracking results obtained from field tests indicated that the root mean squared (RMS) error of the tractor lateral deviationwas less than 0.03 m, and the maximum lateral deviation was less than 0.1 m when the tractor was traveling on straightor slightly curved paths at speeds up to 3.5 m/s. The results verified that this dynamic path search algorithm could satisfy theneed to navigate an autonomous tractor accurately tracking the desired path to perform agricultural operations.