Measurement and analysis methods for determination of effective swath width from unmanned aerial systems

Authors: Fritz, Bradley - Brad; Martin, Daniel - Dan

Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2020
Publication Date: 5/21/2021
Citation: Fritz, B.K., Martin, D.E. 2020. Measurement and analysis methods for determination of effective swath width from unmanned aerial vehicles. In: Elsik, C.M., editor. Pesticide Formulation and Delivery Systems: 40th Volume, Formulation, Application and Adjuvant Innovation. West Conshohocken, PA: ASTM International. p. 62-85. https://doi.org/10.1520/STP162720190132.
DOI: https://doi.org/10.1520/STP162720190132

Interpretive Summary: With an increasing interest and adoption rate of unmanned aerial spray systems, methods and standards that can be used to understand the impact of system parameters and operational practices on spray deposition patterns is critical to achieving biologically effective applications. Starting from existing standards developed optimize manned aerial application systems for deposition uniformity, field trials were conducted measuring spray distribution patterns from unmanned aerial spray treatments and the data used to evaluate the standard’s applicability. While the current standards proved inadequate, they provided a framework from which additional analysis methods were developed to provide improved operational guidance for optimizing unmanned aerial spray systems in large-scale, broadcast applications of agricultural production and protection products.

Technical Abstract: The interest in using unmanned aerial platforms for agrochemical spray applications continues to rise, however methods for assessing the deposition patterns for these systems vary significantly across the current literature base. As with any application platform, understanding the effect the system and its operational parameters has on spray deposition rate and uniformity across the application site and developing an operational understanding of the appropriate flight line spacing (also known as the effective swath width) is critical to a successful broadcast application. This work presents results from efforts to scale and adapt the available standards for the measurement of swath width and deposition uniformity from unmanned aerial systems. The small platform size of current UAV systems being considered for broadcast applications, along with the limited nozzle numbers used potentially provides for deposition patterns that vary across the time of application making it difficult to achieve acceptable progressive broadcast deposition uniformity. Deposition uniformity and the applied spray rate from finer spray treatments were less sensitive to changes in swath width than coarse spray applications. The inherent variability between the replicate passes for all spray treatments made the use of current standard methods problematic in capturing adequate data to provide guidance on appropriate swath widths for use is making precise, uniform broadcast spray applications. Improvements in guidance were found with an increased number of replicates and analysis methods that incorporated the random variance between spray passes. The results provide a foundation for further improving methods for measuring spray deposition uniformity and operational guidance for broadcast applications using UAVs, which will be key in determining appropriate nozzle selection, operation and placement and corresponding flight parameters that result in precise, constant application rates that are biologically effective.