Tactical ballistic missile tracking using the interacting multiple model algorithm

The problem of tracking a tactical ballistic missile is complicated by the varying target dynamics in the boost, exo-atmospheric and endo-atmospheric phases of flight. A single Kalman filter tuned for constant velocity or constant acceleration is not based upon the correct underlying physical model of these dynamics. By including models with all of the correct dynamics, an interacting multiple model (IMM) simultaneously weights all of them and adapts to the one most closely matching the data based upon measurement residuals. A multiple-sensor application of this algorithm requires either a single IMM driven by measurements from all sensors (measurement fusion) or an IMM for each sensor driven by its own measurements, followed by fusion across sensors (track fusion). This paper develops a tactical ballistic missile tracker within an IMM framework and gives an example of the measurement fusion approach for a simulated trajectory and simulated sensor geometry.