Development of a PWM precision spraying controller for unmanned aerial vehicles

This paper presents a new Pulse Width Modulation (PWM) controller for Unmanned Aerial Vehicle (UAV) precision sprayer for agriculture using a TL494 fixed-frequency pulse width modulator together with a data acquisition board and developed software. An UAV can be remotely controlled or flown autonomously by pre-programmed flight plans. The PWM controller was implemented through the guidance system on the UAV with control commands sent between the UAV helicopter and the ground control station via a wireless telemetry system. The PWM controller was tested and validated using LabVIEW 8.2. Several analyses were performed in a laboratory to test different control signals. The results show that the PWM controller has promise as a higher precision technique for spray applications, which will improve efficiency of pesticide application, especially in crop production areas.