Kalman Filter Design for an Inertial Navigation System Aided by Non-Synchronous Navigation Satellite Constellations
AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB
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The report is a Kalman filter design study for the proposed Integrated Navigation SatelliteInertial System INI. Primary emphasis is placed upon determination of the best filter state variable vector and investigation of various measurement rates using external range measurements from a set of 27 non-synchronous satellites. The INI system errors are assumed to be represented by a 44 state linear system model, and the filter operates without benefit of an altimeter. A one-hour INI flight at constant speed and altitude over a great circle path is simulated on the digital computer and filter designs are compared by plotting the system position, velocity, and attitude error covariances versus time. A 15 state filter with weak coupling terms removed is determined to provide the best tradeoff between accuracy and computational burden. Filter performance is compared at 5, 15, 30, 60 and 90 second measurement update rates. Additionally, optimal sequencing of satellite observables is shown to provide improved performance.