The Impact of Attitude on Image-Based Integrity

Craig Larson and John Raquet

Abstract:	The value of Global Navigation Satellite Systems (GNSS) in a multitude of both military and civilian navigation and timing applications has been indisputably shown over the last twenty plus years. Increased dependence on GNSS has driven the need for risk management in using these systems for critical operations. One example risk reduction is through use of an integrity monitoring process, a process which predicts the impact of a worst case or minimal detectable bias error on the navigation position error. The navigation community has spent nearly two decades in development of GNSS integrity algorithms and continues to refine methodologies and investigate new approaches. As a result, the concept of integrity has been formalized for GPS to encompass fundamental criteria, including the ability to detect measurement errors and notify the user when the system should not be used because of potentially corrupt measurements. More recently, researchers have begun investigating the potential use of image-based navigation systems for applications where GNSS signals are not available or should not be used. Independence from external radio-frequency transmissions and potentially low-cost implementations of camera and image processing suites are among the key advantages of these newer systems. However, while larger issues of integrity are seemingly well-understood for many GNSS applications, to the best knowledge of the authors, no one has fully addressed rigorous integrity quantification with respect to image-based navigation systems. This paper details the research into the impact of attitude in an image-based integrity framework. With image measurements, the attitude can either be solved for directly, or it can be considered known (such as if the camera was mounted to an INS with a sufficiently-good attitude determination capability to be considered a known attitude). The paper then describes how image-based integrity can be calculated for both known and unknown attitude cases. The benefit of having known attitude is then quantified. These results show that, from an integrity perspective, there is a significant benefit of having known attitude information. This result implies that for cases in which integrity is important, it is highly valuable to have some sort of attitude measurement capability (such as an inertial navigation system).
Published in:	Proceedings of the 2010 International Technical Meeting of The Institute of Navigation January 25 - 27, 2010 Catamaran Resort Hotel San Diego, CA
Pages:	135 - 147
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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