An Improved Sensor Level Integrity Algorithm for GPS/INS Integrated System

U.I. Bhatti

Abstract:	GPS is the most widely used satellite navigation system. By design, there is no provision for real time integrity information within the Standard Positioning Service(SPS). However, in safety critical sectors like aviation, stringent integrity performance requirements must be met. This can be achieved using the GIC (GPS Integrity Channel) or RAIM (Receiver Autonomous Integrity Monitoring) or both. RAIM, the most cost effective method relies on data consistency, and therefore requires redundant measurements for its operation. An external aid to provide this redundancy can be in the form of an Inertial Navigation system (INS). This should enable continued performance even during RAIM holes (when no redundant satellite measurements are available). This paper discusses integrated system architectures and current integrity algorithms to deal with system failures. A simulation for a typical aircraft trajectory is developed. Using the simulated output of the aircraft based INS and GPS receiver, current integrity algorithms are evaluated. The performance is assessed for the most difficult case of failures; slowly growing errors (SGE). A new algorithm based on detection of the growth rate of a typical test statistic is presented. Results show that the new algorithm detects slowly growing ramp-type failures faster than the current methods. This will enable early detection of such errors for enhanced integrity performance.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	3012 - 3023
Cite this article:	Bhatti, U.I., "An Improved Sensor Level Integrity Algorithm for GPS/INS Integrated System," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 3012-3023.
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