Improvements in GPS Integrity Monitoring for Non-precision Sole Means of Navigation Using Hybrid GPS-INS

Abdelrazak Younes, Igor Nikiiorov, Abdelahad Benhallam

Abstract:	GPS by itself is unsatisfactory as a sole means of navigation for civil aviation users. ‘Receiver Autonomous Integrity Monitoring’ @IIvl) has been propmed whereby a receiver makes use of redundant satellite information to check the integrity of the navigation solution. Two types of algorithms can provide RAIM fimction: the currently used snapshot methods only process the current measurements and the sequential ones process all past and current measurements. ‘he principal limitation of snapshot RAIM is its availability. Inde~ for a Non-Precision Approach (NPA) phase of flight there are periods when the five satellites (with sufficiently good geometry) nquired for fault detection are not available; these periods sometimes last more than 10 minutes. As well, the fault detection and exclusion function can be unavailable fm mom than an hour. Use of sequential algorithm will with no doubt impmve this situation but will probably not be sufficient to allow GPS to meet Civil Aviation requirements. As a solutioL an attempt could be made to hybridim GPS with an Inertial Navigation System (INS). Two solutions for hybridization are considered. The simplest solution is to use the INS as a primary system of navigation and to update it periodically with the GPS solution. ‘Ihe GPS position must then be camsildlymonitored by a sequentialalgorithm that tests the least squares residuals of the GPS solution. The integrity of the INS must then be monitored by another algorithm. The other solution is to hybridize more finely the two systems by using a bank of Kahnan filters that take into account all the measurements Iiom GPS satellites and INS. Then a sequential algorithm will try to detect and isolate any faulty GPS channel or INS sensor,
Published in:	Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997) September 16 - 19, 1997 Kansas City, MO
Pages:	509 - 518
Cite this article:	Younes, Abdelrazak, Nikiiorov, Igor, Benhallam, Abdelahad, "Improvements in GPS Integrity Monitoring for Non-precision Sole Means of Navigation Using Hybrid GPS-INS," Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997), Kansas City, MO, September 1997, pp. 509-518.
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