Performance of Integrity Monitoring Techniques for Shipboard Relative GPS Landing Systems

Christopher Mather, Alex Macaulay, Steve Mole and John Goddard

Abstract:	QinetiQ has recently undertaken a programme of research into the technology readiness and feasibility of generic GPS based shipboard recovery architectures and concepts on behalf of the UK Ministry of Defence (MoD). In parallel with this activity, QinetiQ has also undertaken a risk reduction and flight test demonstration activity, as part of the System Development and Demonstration (SDD) phase of the Joint Strike Fighter (JSF) programme. The Autoland Demonstration, undertaken in collaboration with the UK Joint Combat Aircraft IPT, the JSF Joint Program Office (JPO) and the Joint Precision Approach and Landing System (JPALS) programme, was undertaken to investigate the Concept of Operations (CONOPS) for automatic shipboard approach and vertical landing for the STOVL JSF (F-35B). A series of flight trials, involving the QinetiQ Vectored-thrust Aircraft Advanced Control (VAAC) Harrier fly-by-wire research aircraft and a Royal Navy Invincible Class Aircraft Carrier (CVS), has been conducted to obtain validation data, culminating in a world-first automatic landing of a STOVL aircraft on a ship. Through a combination of offline trial-data analysis and real-time trials assessment this paper seeks to show initial results of an evaluation of candidate architectures for GPS based shipboard recovery. Candidate Shipboard Relative GPS (SRGPS) architectures are described, including associated integrity monitoring schemes and solution generation techniques. A subset of these architectures has been implemented as part of the real-time trials assessment activity of automatic shipboard approach and vertical landing of an advanced STOVL aircraft. Extensive development and evaluation work has been conducted on GPS integrity monitoring architectures by the Federal Aviation Authority (FAA) under the Local Area Augmentation System (LAAS) programme. This work provides a starting point for feasible SRGPS architectures; however modification is required to overcome the particular demands of operation on a moving platform at sea. The major differences between the LAAS integrity monitoring architecture and the candidate architectures evaluated for SRGPS are described. The impact of shipboard hosting of the associated monitors, consistency checks and integrity tests is reported along with an assessment of the perceived error sources. Shipboard data from the Autoland Demonstration will be used to undertake offline analysis of the candidate architectures to validate the outline error budget assumptions and evaluate thresholds for the various integrity monitoring algorithms. Analysis of the predicted alarm limits will also be undertaken and reported. In addition, analysis of the real-time aspects of the candidate architectures will be undertaken and reported using collected data and results from the Autoland Demonstration flights.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	2882 - 2894
Cite this article:	Mather, Christopher, Macaulay, Alex, Mole, Steve, Goddard, John, "Performance of Integrity Monitoring Techniques for Shipboard Relative GPS Landing Systems," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 2882-2894.
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