Double look-ahead reference point control for autonomous agricultural vehicles

Abstract

A simple automatic path tracking system is developed to satisfy the typical requirements of an unmanned agricultural tractor application based on two look-ahead reference points (2-LARP) on the desired path. The main objective of the proposed control system is to track a desired path within reasonable tolerances of a typical farming process including considerable slippage. The employed look-ahead reference points provide compensation for the centrifugal forces and reduction of the peak lateral deviation due to curvature transition, using only simple arithmetic operations. Extensive numerical tests were carried out on the computer simulation of the system dynamics driven by the proposed control method. Simulation results indicate enhancements in vehicle manoeuvrability. Tests indicated that the peak lateral displacement error at the curvature transitions is reduced to one fifth of single LARP error. ► Simple path tracking for agricultural vehicles using 2 look-ahead reference points. ► Lateral deviations similar to an exponentially decaying 6th order dynamic system. ► One look-ahead reference compensates for centrifugal forces over large speed range. ► Second look-ahead reference reduces the peak deviation at curvature transitions. ► The proposed controller reduces the peak error at curvature transitions.