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Short- and long-term dynamic accuracies determination of satellite-based positioning devices using a specially designed testing facility

Gavric, M., Martinov, M., Bojic, S., Djatkov, Dj., Pavlovic, M.
Computers and electronics in agriculture 2011 v.76 no.2 pp. 297-305
accuracy, dynamic testing, global positioning systems, mathematical models
Short-term dynamic accuracy is one of the most significant parameters for agricultural application of satellite-based positioning on straight segments. This is an important characteristic of guidance devices for every user. Two standards are proposed for dynamic testing of satellite-based positioning devices for utilization in agriculture. Previous approaches were typically based on the use of RTK records as a reference for error calculation. A test procedure based on a highly precise testing facility was developed, having a mechanical offset of the test cart less than 0.002m. The new mathematical approach for straight line segment definition, based on two representative points was developed. This approach enables error-free calculation of off-track errors and determination of U-turn influence based on two additional parameters. Long-term testing was performed (24h), using a Garmin GPS 18 device for test validation. The obtained results showed that this method can be successfully used for testing dynamic characteristics of GNSS devices. The results were as follows: mean value of the off-track errors was −0.39m, standard deviation of all measured off-track errors was 1.51m, being 1.3m in 95% of the measured off-track errors. The pass-to-pass average error was 0.90m, being under 0.662m in 95% of the detected passes. The designed facility and developed procedure can also be successfully applied to the testing of high precision devices, e.g., RTK.