摘要: This paper presents the main results of the researchactivities carried out by the Italian Air Force Flight TestCentre in collaboration with the University ofNottingham and Cranfield University in the area ofGNSS Avionics Based Int... 展开 This paper presents the main results of the researchactivities carried out by the Italian Air Force Flight TestCentre in collaboration with the University ofNottingham and Cranfield University in the area ofGNSS Avionics Based Integrity Augmentation (ABIA).This research included design, integration andexperimental flight test activities on the MB-339CD,TORNADO and TYPHOON aircraft, as well as thedevelopment of a novel approach to the problem ofGNSS ABIA for mission- and safety-critical air vehicleapplications and for multi-sensor avionics architecturesbased on GNSS. As soon as the validity of the ABIAconcept was established, a prototype system wasdeveloped for use in flight test applications. This systemis capable of alerting the pilot when the criticalconditions for GPS signal loss are likely to occur,within a specified maximum time-to-alert. In thisABIA prototype, the aircraft on-board sensors provideinformation on the aircraft relevant flight parameters(navigation data, engine settings, etc.) to an IntegrityFlag Generator (IFG), which is also connected to theon-board GPS receiver. The IFG can be incorporatedinto one of the existing airborne computers or can be adedicated processing unit. Using the available data onGPS and the aircraft flight parameters, integrity signalsare generated which are displayed on one of the cockpitdisplays and sent to an Aural Warning Generator(AWG). At the same time, the deviation from the idealflight path is computed taking into account thegeometry and the tracking status of the available GPSsatellites, together with the flight test missionrequirements and the information provided by the onboardavionic sensors. Current research is extendingthe results obtained from flight tests to the design of amore advanced ABIA system suitable for manned andunmanned aircraft applications. Mathematical modelshave been developed to describe the main causes ofGNSS signal outages and degradation in flight, namely:antenna obscuration, multipath, fading due to adversegeometry and Doppler shift. Adopting these models inassociation with suitable integrity thresholds andguidance algorithms, the ABIA system is able togenerate integrity cautions (predictive flags) andwarnings (reactive flags), as well as providing steeringinformation to the pilot and electronic commands to theaircraft/UAV flight control system. These featuresallow real-time avoidance of safety-critical flightconditions and fast recovery of the required navigationperformance in case of GNSS data losses. In otherwords, this novel ABIA system addresses all threecornerstones of GNSS integrity augmentation inmission- and safety-critical applications: prediction(caution flags), reaction (warning flags) and correction(alternate flight path computation). 收起