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Evaluation of spray accuracy for an experimental greenhouse variable-rate spray system

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

Citation:  2018 ASABE Annual International Meeting  1800183.(doi:10.13031/aim.201800183)
Authors:   Tingting Yan, Heping Zhu, Li Sun, Xiaochan Wang, Peter Ling
Keywords:   Automation, Spray accuracy, Greenhouse, Pesticide spray equipment, Variable rate.

Abstract. An experimental spray system for greenhouse applications was developed with an integration of a high-speed laser scanning sensor to control real-time spray outputs of 12 individual nozzles on a 3.60 m long horizontal spray boom. Each nozzle was coupled with a pulse width modulated solenoid valve to discharge variable rates based on the presence and plant canopy structures. Laboratory tests were conducted to validate the control system accuracies in spray response time, spray volume and activation by single and group of objects under the combinations of three laser detection heights (0.5, 0.75 and 1.0 m), and five constant travel speeds (1.6, 2.4, 3.2, 4.0 and 4.8 km h-1). A high-speed video camera recorded sequential images to determine nozzle activations in discharging sprays on target objects after the laser sensor detected the objects. The laser detection height and travel speed had slight influences on times when nozzles started and stopped spraying objects. The nozzles started spraying in a range from 33±36 mm to 83±62 mm before reaching the target objects, and stopped spraying in a range from 13±30 mm to 84±61 mm after passing the objects, ensuring the objects being fully covered by the sprays. The spray volume corresponded to the object sizes well. The difference between VD and VR ranged from 1.9 to 2.7 mL for all the objects. At the same time, the nozzles could be activated precisely by the object presence. The spray control system performed with higher accuracy at lower speeds. The abstract is often the only part of the paper to be read, so include your major findings in a useful and concise manner. Include a problem statement, objectives, brief methods, quantitative results, and the significance of your findings. The abstract should be no more than 250 words long.

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