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Analytical Redundancy Using Kalman Filters for Rocket Engine Sensor ValidationThe use of sensor redundancy is crucial in aerospace systems to maintain safe, reliable operation. While hardware redundancy is more common in application, analytical redundancy can provide a viable alternative in systems where the installation of multiple redundant sensors is not viable. To this end, the use of Kalman filters to analytically validate sensor measurements within rocket engines was explored. First, a dynamic model of the RS 25 engine, a derivative of the Space Shuttle Main Engine (SSME), was reduced to a subset of relations, focused around the main combustion chamber pressure. These relations were used within the Kalman filter algorithm to generate an estimate of sensor measurements to be compared with true measurements for data validation purposes. By using a bank of Kalman filters, the residuals between the estimated and true measurements were used to detect and isolate sensor faults. Through fault simulations, the sensor validation performance of this Kalman filter bank design was compared to a hardware redundancy check. Sensor bias and drift faults of various magnitudes were injected into nominal RS 25 engine test data. Results for both approaches show comparable fault detection with most bias faults found nearly instantaneously by both algorithms. Drift fault detection results show certain cases where one algorithm is faster than the other. The key advantage of the Kalman filter algorithm is shown in fault isolation performance where it can isolate faults between two redundant sensors while the hardware redundancy comparisons cannot.
Document ID
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Nicklaus O. Richardson
(University of Illinois at Urbana Champaign Urbana, Illinois, United States)
Edmond Wong
(Glenn Research Center Cleveland, Ohio, United States)
Kevin Melcher
(Glenn Research Center Cleveland, Ohio, United States)
Date Acquired
April 3, 2020
Publication Date
October 1, 2020
Publication Information
Subject Category
Space Transportation And Safety
Spacecraft Instrumentation And Astrionics
Launch Vehicles And Launch Operations
Report/Patent Number
Funding Number(s)
WBS: 585777.
Distribution Limits
Public Use Permitted.
Technical Review
NASA Technical Management
sensor validation
sensor qualification
analytical redundancy
Kalman filter
rocket engine
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