Raytheon Company

Mark S Moellenhoff

Thomas K Lo

Nikki J Lawrence

Joshua A Whorf

A tracking system controls an aimed device ( ) to keep it aimed at a target ( ). A control system ( ) determines when the tracker has lost its lock on the target ( ) by comparing the target's instantaneous acceleration with its median acceleration. When the difference exceeds a predetermined threshold, the system searches backwards through a chronological buffer until it finds position data which antedate the receipt of inaccurate position data from the tracker. A second-order filter such as a Kalman filter is used to provide estimated target states. The difference between a time updated output from the second-order filter ( ) and the present measured state from the tracking device is low pass filtered to provide a measurement of the instantaneous acceleration of the target. The buffer ( ) stores position, velocity, and median acceleration values covering a span of time at least about twice as long as the time required to determine that a breaklock has occurred.

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Tucson, AZ, United States of America

Mark S Moellenhoff