Decentralized Filtering and Redundancy Management/Failure Detection for Multisensor Integrated Navigation Systems

Thomas Kerr

Abstract:	The problem addressed here is failure detection and redundancy management in avionics applications of integrated navigation involving coordinated use of multiple simultaneous sensor subsystems such as GPS, JTIDS, TACAN , VOR/DME, ILS, an Inertial Navigation System (INS ), and possibly even Doppler AMRS. A brief high level survey i s provided to assess the status of those techniques and methodologies advertised as already avail able for handling the challenging real-time failure detection, redundancy management , and Kalman filtering aspects of these systems with differing availabilities, differing reliabilities, differing accuracies, and differing information content/sampling rates. Following the status review, a new failure detection/redundancy management approach i s developed based on voter/monitoring at both the raw data and at the filtered-data level , as well as using additional inputs from hardware BIT ·and from specialized tests for subsequent failure isolation in the case Of ambiguous indications. The technique developed involves use of Gaussian confidence regions to reasonably account for the inherent differences in accuracy between the various sensor subsystems. On-line estimates of covariances from the Kalman filter are to be used for this purpose (when avail able) . A technique is provided for quantitatively evaluating both the probability of detecting failed component subsystems and the probability of false alarm to be incurred , which i s then to be traded-off as the basis for rational selection of the thresholds used in the automated decision process. Moreover, the redundancy management procedure is demonstrated to be amenable to pilot/navigation operator prompting and override, if necessary. A structure to accommodate differing rates of subsystem assessment and· tally is developed and alternative designs for navigation architectures are offered based on likely subsystem utilization and newly emerging concepts in decentralized Kalman filtering. Many of the decentralized filtering concepts are only now economically feasible for real-time implementation due to recent availability of commercial parallel processing chips and/or VHSIC compatible systolic array versions of all the requisite algorithms and transformations necessary to support such Kalman filter mechanizations i n a few chips.
Published in:	Proceedings of the 1985 National Technical Meeting of The Institute of Navigation January 15 - 17, 1985 San Diego, CA
Pages:	191 - 208
Cite this article:	Kerr, Thomas, "Decentralized Filtering and Redundancy Management/Failure Detection for Multisensor Integrated Navigation Systems," Proceedings of the 1985 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1985, pp. 191-208.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In