Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

An Electronic Flow Control System for a Variable-rate Tree Sprayer

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2012 Dallas, Texas, July 29 - August 1, 2012  121337321.(doi:10.13031/2013.41766)
Authors:   Hui Liu, Heping Zhu, Yu Chen, Yue Shen, H Erdal Ozkan
Keywords:   Precision sprayer, Laser sensor, Pulse width modulation, Specialty crop

Precise modulation of nozzle flow rates is a critical measure to achieve variable-rate spray applications. An electronic flow rate control system accommodating with microprocessors and pulse width modulation (PWM) controlled solenoid valves was designed to manipulate the output of spray nozzles independently to match tree structures which would be detected with a wide-range laser scanning sensor. The PWM signals to control nozzle flow rates were generated by the microprocessors based on laser sensor detections. Multi-channel driver and protection circuits for activating solenoid valves were developed to modulate variable-rate outputs in real time. An embedded computer PC/104 along with a touch screen was used to process control algorithms and to fulfill communications between the operator and the control system. Laboratory tests demonstrated that the flow rate control system was able to achieve linear nozzle outputs with the duty cycle of PWM-controlled solenoid valves.

(Download PDF)    (Export to EndNotes)