A Fault Tolerant Technology Concept for Radio Navigation Systems

Graham W. Casserly

Abstract:	This is an exploratory paper which considers the potential application of fault tolerant technology to radio navigation systems. It concentrates on the position determination function of radio navigation systems to demonstrate the method. The technology is a direct extension of the fault tolerant technology which is used in the inertial navigation area to provide the detection of a problem and the identification of the problem element. The extension is necessary because, in the case of radio navigation systems, the geometrical influences are time varying. Therefore, the coefficients that appear in the sets of fault tolerant consistency equations must be periodically recalculated as a user platform moves through the reference system. The final result is a more general time varying case which contains the stationary fault tolerant case as a subset. The approach here, as in other fault tolerant technology efforts, relies upon the use of redundant numbers of sensors to allow the information consistency checks to be made. The ability to include a variety of navigation sensors in the concept is approached by characterizing the differential properties of the measurement functions in terms of their gradients. This allows the development of a generalized computational process for both the position determination function and the fault tolerant signal processor. Generalization of the computational processing leads to the possibility of embedding the processing in firmware. The results provide strong insight into the architectural aspects of a practical system for implementing the method.
Published in:	Proceedings of the 1988 National Technical Meeting of The Institute of Navigation January 26 - 29, 1988 Santa Barbara, CA
Pages:	30 - 37
Cite this article:	Casserly, Graham W., "A Fault Tolerant Technology Concept for Radio Navigation Systems," Proceedings of the 1988 National Technical Meeting of The Institute of Navigation, Santa Barbara, CA, January 1988, pp. 30-37.
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