AUTONOMOUS GREENHOUSE SPRAYER VEHICLE USING MACHINE VISION AND LADAR FOR STEERING CONTROLS

Abstract

A six-wheel differential steering vehicle was designed and built to provide a vehicle platform for a greenhousesprayer. The vehicle was designed to operate as a self-contained system, which would carry the power supply, spray tank,pump, and boom. Independently controlled DC motors were used to provide differential steering for the vehicle. A fuzzylogic-based proportional-derivative controller was developed and tested to navigate the vehicle through the aisle way usingmachine vision and laser radar range information. The vehicle was tested under three different path configurations using aflexible curvature track. The track was configured for straight, moderate, and heavy curved conditions. Path trackingcomparisons were made between the vision-based control and a laser-radar- (ladar-) based control. The error was monitoredusing the ladar as the most accurate measure of the position error between the path centerline and the vehicle centerline.<br><br>Error comparisons were made using RMS error and average instantaneous error. It was found that the ladar-based controlwas the better overall guidance system under all track conditions. Although, average errors were fairly low at approximately10 mm, the maximum errors left room for improvement at approximately 40 mm.