Analysis and Quantification of GNSS/INS Error Sources in an Automotive Context

Erin Kahr, Graeme Garner, Yannick Stebler, Edmond Leahy, Paul Gratton, Felipe Cupido, Lance de Groot

Abstract:	Designing an integrated GNSS system for the autonomous driving industry comes with a need for functional safety, similar to that of the aviation industry. However, while traditional aviation solutions, such as satellite-based augmentation systems (SBAS), operate on carrier smoothed code measurements and have protection level requirements at tens or hundreds of metres, autonomous driving requires lane-level positioning at the same level of safety. To answer this need, Hexagon has developed a precise point positioning (PPP)-based positioning engine library. The library takes PPP corrections, as well as automotive-grade GNSS, IMU, and other vehicle sensors as input and provides real-time positioning solutions alongside protection levels. The protection levels are calculated using solution separation receiver autonomous integrity monitoring (RAIM) and contain the true position error to a known level of probability per exposure time, referred to as the total integrity risk. In order to prove the total integrity risk of the system, a quantified fault tree detailing the possible faults and corresponding mitigations in the system was created. Numerous methods were used to populate the probability risks in each node of the tree to quantify the entire fault tree branches: fault analysis using overbounding standard deviations, mitigation analysis by largescale statistical injection of observed and theoretical faults, and statistical modelling of the entire system. The calculated probabilities in turn drove changes in the system designs of both the correction service and the positioning engine library, ultimately iterating to produce a product that meets both the performance and safety needs of autonomous driving, and which is developed to automotive industry standards.
Published in:	Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025) September 8 - 12, 2025 Hilton Baltimore Inner Harbor Baltimore, Maryland
Pages:	1427 - 1439
Cite this article:	Kahr, Erin, Garner, Graeme, Stebler, Yannick, Leahy, Edmond, Gratton, Paul, Cupido, Felipe, de Groot, Lance, "Analysis and Quantification of GNSS/INS Error Sources in an Automotive Context," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 1427-1439. https://doi.org/10.33012/2025.20240
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