ASABE Technical Library - Abstract

Abstract. An intelligent variable-rate air-assisted sprayer was developed to automatically adjust spray outputs to match tree crop shape, size and foliage density for precision pesticide spray applications. The sprayer was an integration of an embedded computer, a 270° radial-range laser sensor, a travel speed sensor, an automatic flow rate control unit, multiple pulse width modulated (PWM) nozzles and an air-assisted spray delivery system. An algorithm written with VC++ program was developed and saved in the embedded computer to collect bilateral crop structure data from the laser sensor and the travel speed sensor in real time, reconstruct 3-dimensional surfaces of crops, and calculate the amount of sprays needed from each nozzle for its corresponding crop section. The information on the amount of sprays was sent to the automatic flow rate control unit to manipulate the flow rates of all nozzles simultaneously through PWM-controlled solenoid valves. Field experiments were conducted to compare the intelligent sprayer prototype and a constant-rate sprayer for their spray deposition quantity and coverage uniformity in commercial nurseries. Test results demonstrated the new sprayer had the capability to control spray outputs to match different tree structures with sprayer travel speeds from 3.2 to 8.0 km h^-1, and was able to save the amount of tank mixtures by more than 50% compared to the constant-rate applications.