Common Kalman Filter: Fault-Tolerant Navigation for Next Generation Aircraft

Peter V. W. Loomis, Neal Carlson, Michael P. Berarducci

Abstract:	Common Kalman Filter is an ongoing U.S. Air Force Avionics Laboratory program to develop, simulate. and evaluate computational techniques and software architectures that will enhance the robustness and reliability of Integrated navigation systems for the next generation of military aircraft. The project addresses four areas: filter mechanization and architecture including decentralized filtering; fault detection and isolation; system software reconfiguration strategies; and exploitation of advanced avionics technologies such as VHSIC, parallel processing and Pave Pillar data bus architectures. Problems of Kalman filter throughput, cascaded filter instability, and the high rate data interface requirements of decentralized filtering are being addressed. Decentralized filtering is a natural technique for tying together the many sensors of the modern navigation suite aboard the next-generation fighter. Each navigation sensor typically has been designed as a locally autonomous navigation system, with its own dedicated Kalman filter. The decentralized filter framework ideally would improve fault tolerance and fault recovery by retaining the autonomy of the filters and at the same time, preserve navigation accuracy by maintaining a central master filter with a globally optimal or near optimal solution, while enhancing throughput in a distributed processing environment. The decentralized, fault-tolerant filter scheme described here demonstrates the Carlson technique of trading off optimality of the master solution to gain an extra measure of fault tolerance and throughput. The small accuracy loss due to suboplimality is more than compensated by the increase in robustness of the navigation solution. The navigation sensor suite around which this is designed represents the avionics suite of the next-generation fighter aircraft, with dual inertial units, GPS, JTIDS, SIT AN, and other landmark reference sensors. This paper describes the CKF design which is nearing maturity and Is currently entering a computer simulation test cycle. Approaches to sensor information requirements definition, local sensor integration/filtering, master filter modeling, and automatic fault detection/isolation and system reconfiguration are discussed. Failure modes are described which will be the basis for the evaluation of CKF failure response in subsequent simulations.
Published in:	Proceedings of the 1988 National Technical Meeting of The Institute of Navigation January 26 - 29, 1988 Santa Barbara, CA
Pages:	38 - 45
Cite this article:	Loomis, Peter V. W., Carlson, Neal, Berarducci, Michael P., "Common Kalman Filter: Fault-Tolerant Navigation for Next Generation Aircraft," Proceedings of the 1988 National Technical Meeting of The Institute of Navigation, Santa Barbara, CA, January 1988, pp. 38-45.
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