Double look-ahead reference point control for autonomous agricultural vehicles

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.