Swath pattern analysis from a multi‐rotor unmanned aerial vehicle configured for pesticide application

Abstract

BACKGROUND Although unmanned aerial vehicles (UAVs) are increasingly used to deliver small‐scale aerial pesticide applications, there remains uncertainty over their efficiency in terms of uniformity of spray deposition and their application efficiency. Consequently, a field study was designed to quantify factors influencing the uniformity of spray deposition from a multi‐rotor UAV that is operated commercially in New Zealand. Two sampling systems for measuring spray deposition, a continuous horizontal string and steel plates placed on the ground were compared. RESULTS The spray deposit distribution characteristics and calculated lane separation values (distance between flight lines that produces a maximum coefficient of variation of 30% for spray deposits) were strongly influenced by wind speed, nozzle position, release height, ground speed and droplet size. Lane separation values ranged from 1 to > 5 m. Swath distribution parameters (spread and position of peak deposition) derived from plates were not significantly different from those derived from string. However, total deposition on strings relative to plates increased with small droplets. Reducing plate sampling intensity from 0.25 m intervals to 0.5 m and even 1.0 m had only a minor effect on estimates of swath parameter values. CONCLUSIONS The potential for precision spraying from UAV platforms has yet to be achieved with improvements required in hardware and software. Further, mechanistic models are needed to quantify how complex interactions among multiple operating and meteorological variables influence spray deposition. © 2019 Society of Chemical Industry

Evaluation of an unmanned aerial vehicle as a new method of pesticide application for almond crop protection

“…Hence, UAV application technology, which allows higher operational efficiency combined with comparable pest control results, emerges as a new approach to supplement or displace the traditional ground and aerial spraying practices. [10][11][12][13][14] Concurrent with the evolving UAV technology are the demands for correct and safe application of pesticides under challenged environmental and biological conditions. 10 Certainly, orchard environments with tall trees and expansive canopies present challenges for achieving adequate pest control for any method of application, especially when targeted insecticide delivery (nut deposit) is desirable.…”

“…Meanwhile, regulatory changes in labor practices, such as limitation on workday length and higher minimum wages, are driving more automation, in general, for agriculture field operations. Hence, UAV application technology, which allows higher operational efficiency combined with comparable pest control results, emerges as a new approach to supplement or displace the traditional ground and aerial spraying practices 10‐14 …”

“…Such constraints require characterization of the drone application performance throughout multiple spraying events relevant to the complexity of hull‐splitting stages. While water sensitive paper and fluorescent tracer dyes are commonly used in spray quality evaluation, 13 pesticide residues on the spray targets and subsequent biological performance may also be critical for characterizing the effectiveness of a method of application. Thus, a comprehensive investigation that includes the combination of multiple evaluation tools to measure the suitability of drone spray in almonds compared to commercial ground air‐blast application, was conducted.…”

Effect of Application Height and Ground Speed on Spray Pattern and Droplet Spectra from Remotely Piloted Aerial Application Systems

“…Heavily replicated trials are needed to adequately separate out potential differences in effective swath due to independent operational variables such as platform, application height and ground speed. Richardson et al [24] reported a highly variable swath pattern with large unexplained variance despite 65 flights being made with a multi-rotor MG-1 aircraft under varying ground speed, droplet size and application height. Similarly, Shilin et al [25] studied spray deposition profiles of four UAVs with different payload capacities and found highly variable spray distribution patterns.…”

“…Similarly, Shilin et al [25] studied spray deposition profiles of four UAVs with different payload capacities and found highly variable spray distribution patterns. Both Richardson et al [24] and Shilin et al [25] concluded that high precision and efficiency from RPAAS application systems has not yet been realized. It is well recognized that a certain number of replications must be examined on a given experimental area and date to provide an adequate estimate of sampling variance.…”