Raytheon Company

Nikki J Lawrence

Thomas K Lo

Joshua A Whorf

Hagos Teku

Mark S Moellenhoff

A generalized Hough transform is used to acquire and track vehicular targets for missile guidance. This is accomplished by recognizing that most vehicles have silhouettes that may be described as a 'rounded rectangle'. The position and shape of such rounded rectangles is described in terms of 5 parameters (x, y, a, b, &#x3b8;) where x, yare the center coordinates, a,b are the major and minor axis and &#x398; is the orientation. The computation of a five dimensional Hough transform on an image including such a target will produce the five parameters that provide the 'best fit' rounded rectangle to the target. These parameters are then passed to a missile tracker. This capability can be used to improve track gate handoff from the automatic target recognizer (ATR) to the missile tracker, changing aspect ratios of maneuvering targets, limited lock-on after launch (LOAL), aimpoint designation and fire control system to missile seeker handover.

Vehicular target acquisition and tracking using a generalized hough transform for missile guidance

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

Nikki J Lawrence