LABORATORY EVALUATION OF A TURN COMPENSATION CONTROL SYSTEM FOR A GROUND SPRAYER

The ability to compensate sprayer nozzle flow across a horizontal boom has the potential to mitigate the problem of inaccurate chemical application rate due to lateral speed differences when sprayers are turning. A laboratory testing platform and procedure were developed and tested with a commercial turn compensation control system for a ground sprayer. Virtual paths consisting of simulated GPS signals representing right and left turns separated by straight segments were simulated with four turning radii (75%, 125%, 250%, and 500%) based on boom width. Actual application rates from 11 nozzles spread across the boom were measured using load cells in real time and were compared with desired application rate. Mean flow rate and coefficient of variation by nozzle position for each segment of the test paths showed a general consistency between the expected application rate and actual application rate for most nozzles at most cases with a small discrepancy for a few nozzles. Application errors were within the accepted ±10% range specified by ASABE. This study contributes to the formation of a test standard for turn compensation control systems calibration in the future