GROUND SPEED CONTROL OF PESTICIDE APPLICATION RATES IN A COMPRESSED-AIR DIRECT-INJECTION SPRAYER

This article describes a technique to control pesticide application ra tes in direct proportion to varying ground speed for a compressed air direct injection (CADI) sprayer. The CADI sprayer was a closed loop sp rayer in which the liquids were delivered by applying air pressure in the liquid reservoirs. A radar sensor and an oval gear flow meter gave outPut signals proportional to ground speed and pesticide flow rate, respectively. These outputs were used as inputs to a datalogger unit t o compute a difference between the desired and actual flow rates. The datalogger unit activated a stepping motor attached to a pressure regu lator of the sprayer to adjust liquid-reservoir air pressure for obtai ning the desired flow rate. The laboratory and field testing of this u nit indicated that the desired flow rate of a simulated pesticide was achieved within reasonable cycles of the control program without syste m oscillation.