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A new position-based method for GPS signal FDI

Authors:Castaldi Paolo, University of Bologna, Italy
Crisci Massimo, European Space Agency - ESA, Netherlands
Zanzi Matteo, University of Bologna, Italy
Topic:7.3 Aerospace
Session:Aerospace Control
Keywords: RAIM, GPS, Identification Scheme, Fault Detection and Isolation, LS

Abstract

Integrity is a critical requirement for aerospace navigation systems. In this paper integrity issues are coped with a new FDI technique implemented by a snapshot RAIM algorithm based on position domain tests. The approach consists of the joint exploitation of all the possible Least Squares (LS) solutions of the GPS linear estimation problem under a single fault on a pseudorange measurement. The loci described by the different LS position solutions by varying the fault size and the faulty satellite are investigated. The exact non linear dependence of the loci from the fault size is considered. No linear approximation is used. This results in a new criterion and algorithm for the faulty satellite isolation. The effectiveness of the proposed method in the isolation of faulty satellite has been compared with a classic FDI method and demonstrated by Montecarlo simulations based on real data.