Construction and Evaluation of Outlet Flow Control System for a Variable Rate Sprayer

This study designed and built an electronic control system to control the chemical concentration of the spray solution in a crop sprayer. The system consisted of a speed sensor, a chemical metering pump, driver, and rotating speed sensor, mixing unit, and electronic control unit. The sprayer provided site-specific crop management after installation of the system on a field sprayer. The direct injection system changed the volume of the mixed chemicals in the carrier fluid (water) to change the concentration of the spray solution. The effects of spray solution pressure and rotational speed of metering pump on pump discharge were evaluated in laboratory testing. A regression relationship was observed between the dependent variable (metering pump discharge) and independent variables. In farm tests, the prescriptive map for concentration of spraying solution was first developed using ArcGIS software. The effects of travel speed (3, 6, and 9 km/h) and spray pressure (3, 4, and 5 bar) on spray concentration error of the first and last nozzles on the right-hand side of the sprayer boom were evaluated. The results showed no significant effect for pressure of sprayed solution and travel speed of the machine on the error of sprayed solution concentration of the first nozzle. The effect of travel speed of the machine was significant on the error of the sprayed solution concentration of the last nozzle. The mean sprayed solution concentration error of the first nozzle was 2.71% and of the last nozzle was 3.56%.