Fusion of Dual Optical Position Solutions for Augmentation of GNSS-based Aircraft Landing Systems

M. Angermann, S. Wolkow, A. Dekiert, U. Bestmann, P. Hecker

Peer Reviewed

Abstract:	The Institute of Flight Guidance runs a research project on image-based airborne positioning systems. Main goal of this research is to guide an aircraft equipped with low cost sensors with medium performance and SBAS (Space-based Augmentation System) capabilities. A predefined glide path must be kept during the approach down to the runway threshold and the position integrity shall be monitored using on-board sensors only. The developed system is intended to cover the gap between applicable decision heights and touchdown of present landing systems by continuous image-based runway detection and optical aided integrity monitoring. In order to meet requirements equivalent to Instrument Landing System (ILS) and Required Navigation Performance (RNP) comparisons between GNSS/INS-based (Global Navigation Satellite System/ Inertial Navigation System) and optical position solutions are performed by the application of static methods and the protection level concept. The optical sensors are integrated in the overall navigation systems by means of the Performance Based Navigation (PBN) concept. The proposed system shall reduce aircraft operation workload in the final phase of landing. Moreover, the system shall provide emergency landing capabilities on single runway operated airports in severe emergencies e.g. in a pilot-unableto-land scenarios. This paper investigates approach of simultaneous provision of two parallel optical position solutions for optical augmented integrity monitoring. The position is obtained by means of Computer Vision from thermal infrared and visual cameras utilizing projective geometry [4]. The system has been evaluated by [1], [2] and [3] using data gathered by real flight campaigns. Due to the complementary working principles of the image sensors, the gathered position samples differ in accuracy and availability depending on the distance to the runway threshold. This work will outline the efficient usage of multispectral image sensors and online analysis for decision handling of the parallel image-based position solution. The algorithm comprises the rating of the position solutions and comparison between each other. Therefore the position’s quality and trustworthiness are analyzed order to maintain necessary levels of accuracy and availability for precision landing approaches. Based on this examination the more valuable optical position solution is selected and used by the navigation unit to perform the integrity monitoring of the GNSS/INS position. If the applicable requirements are met beyond the decision height the landing approach shall be continued. Furthermore, this paper presents different methods for comparison of the extracted solutions provided by the dissimilar optical sensors which need to comply with real-time requirements.
Published in:	Proceedings of the 2019 International Technical Meeting of The Institute of Navigation January 28 - 31, 2019 Hyatt Regency Reston Reston, Virginia
Pages:	283 - 295
Cite this article:	Angermann, M., Wolkow, S., Dekiert, A., Bestmann, U., Hecker, P., "Fusion of Dual Optical Position Solutions for Augmentation of GNSS-based Aircraft Landing Systems," Proceedings of the 2019 International Technical Meeting of The Institute of Navigation, Reston, Virginia, January 2019, pp. 283-295. https://doi.org/10.33012/2019.16694
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