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United States Department of Agriculture

Agricultural Research Service

Research Project: Pesticide Application Technologies for Spray-drift Management, Maximizing In-field Deposition, and Targeted Spraying

Location: Crop Production Systems Research Unit

Title: Portable device to assess dynamic accuracy of global positioning systems (GPS) receivers used in agricultural aircraft

Authors
item THOMSON, STEVEN
item HUANG, YANBO
item Smith, Lowrey -

Submitted to: International Journal of Agricultural and Biological Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 2014
Publication Date: April 29, 2014
Citation: Thomson, S.J., Huang, Y., Smith, L.A. 2014. Portable device to assess dynamic accuracy of global positioning systems (GPS) receivers used in agricultural aircraft. International Journal of Agricultural and Biological Engineering. 7(2):68-74.

Interpretive Summary: Agricultural aircraft used for crop spraying or remote sensing rely on Global Positioning System (GPS) receivers for pilot guidance and determination of field boundaries for termination of spray. In addition, position-triggered remote sensing cameras are being used in Unmanned Aerial Vehicles (UAVs) for precision agriculture. For either case, the dynamic positioning accuracy of the aerial GPS receiver needs to be known. A device was designed to test the dynamic accuracy of Global Positioning System (GPS) receivers used in aerial vehicles, and construction details are presented. An example application evaluated the horizontal accuracy of a GPS receiver placed in the aircraft by matching positioning data with data from the aircraft’s guidance GPS. Example results indicate that a stand-alone GPS receiver exhibited a 2.16s lead in position over that registered by the aircraft’s guidance GPS receiver.

Technical Abstract: A device was designed to test the dynamic accuracy of Global Positioning System (GPS) receivers used in aerial vehicles. The system works by directing a sun-reflected light beam from the ground to the aircraft using mirrors. A photodetector is placed pointing downward from the aircraft and circuitry was designed to trigger an event in the guidance system data file at the aircraft’s location corresponding to the precisely georeferenced position on the ground. Construction details are presented on the mirror-based light reflection system and photo-electronic circuitry designed to trigger an event in the guidance system’s log file. An example application evaluated the horizontal accuracy of a stand-alone GPS receiver by matching dynamic data with data from the aircraft’s guidance system. Example results indicated that a stand-alone GPS receiver showed a 2.16s lead in position over that registered by the aircraft’s guidance system GPS receiver, which had been previously evaluated to be within 0.13 s of RTK-referenced time and position.

Last Modified: 9/10/2014
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