Location: Application Technology ResearchTitle: Development of a laser-guided embedded-computer-controlled air-assisted precision sprayer Author
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2017
Publication Date: N/A
Citation: N/A Interpretive Summary: Architectures and in-row spacing of orchard and nursery trees vary greatly with varieties and growth stages, causing conventional sprayers to produce excessive pesticide waste to the field. A new precision air-assisted variable-rate sprayer was developed with integration of an embedded computer, a high-speed radial-range laser sensor, a ground travel speed sensor, a unique data acquisition and spray control algorithm, an automatic flow rate control unit, multiple pulse width modulated nozzles, and an air-assisted spray delivery system. Field tests with trees in the commercial nursery demonstrated the new sprayer was able to measure tree structures accurately and then adjust the spray output of each nozzle independently to match both tree structures and real-time travel speed. While the sprayer reduced spray volume by 57% to 88% compared to the conventional constant-rate application, it also had greater coverage areas per amount of spray deposits and lower variations in spray deposit quality within canopies. Thus, this innovative sprayer technology will have significant potentials to reduce production costs and improve pesticide application efficiency with minimal environmental impacts for orchard and nursery crops.
Technical Abstract: An embedded computer-controlled, laser-guided, air-assisted, variable-rate precision sprayer was developed to automatically adjust spray outputs on both sides of the sprayer to match presence, size, shape, and foliage density of tree crops. The sprayer was the integration of an embedded computer, a touch screen, a 270° radial-range laser sensor, a travel speed sensor, a unique algorithm, a custom-designed automatic flow rate control unit, and 40 pulse-width-modulated (PWM) nozzles. The accuracy of the sprayer to detect different sized trees and control spray outputs of individual nozzles based on tree structures was tested in a commercial nursery. Spray deposition qualities between variable-rate and constant-rate operational modes of the sprayer were also compared. Test results demonstrated the capability of the sprayer to measure different trees accurately and then control spray outputs of nozzles independently to match tree structure. The outline profile similarity of paired images taken from a digital camera and the laser sensor for three trees ranged from 0.81 to 0.89. To spray trees of different sizes and shapes, the sprayer in the variable-rate mode (VRM) consumed 12.1% to 43.3% of the spray volume that was used in the constant-rate mode (CRM) with an application rate of 468 L ha-1. Moreover, the sprayer in VRM mode had 30% and 55% greater coverage areas per amount of spray deposits than its CRM mode. This innovative sprayer should have significant potentials to reduce pesticide waste, provide sustainable crop protection to grower, and still safeguard the environment.