Hughes Aircraft Company

Arthur K Rue

Gordon T Pope

Steven L Chodos

William G McArthur

Earl L Emerson

Paul E Craft, Jr

Ronald Cubalchini

A sensor may be scanned relative to any arbitrarily selected reference coordinate system by the use of a system including an attitude determination unit, attitude control unit, inertial measurement unit, navigation unit, and a scan generation unit. Methods are also employed, in this system, for reducing errors and increasing the accuracy of the scan of the sensor. These methods include the use of gyroscopes having no cross axis coupling or inherent limit on their angular speed, a Kalman filter to reduce system errors, continually estimating solutions to the strapdown equation, and a dual loop control system utilizing both rate and position signals which issues motion control commands to the sensor.

Measurement and control system for scanning sensors

Point and area target tracking are employed by a dual mode video tracker which includes both a correlation processor (30) and a centroid processor (32) for processing incoming video signals representing the target scene (20) and for generating tracking error signals over an entire video frame. A microcomputer (26) controls the operation of the correlation and centroid processors, as well as a preprocessor (28) which preconditions the incoming video signals. The tracker operates in any of several modes in which the correlation and centroid processors function either independently or cooperatively with each other. The correlation processor generates a reference map in pixel format which is used to produce azimuth and elevation optimal weighting values for each pixel in the field-of-view. The reference map is recursively updated. The track gate for the correlation processor is automatically sized using a gradient function derived from the optimal weighting values. The gradient function is also employed along with difference video to determine correlation tracking status. The correlation and centroid tracking errors may be combined to form a composite signal defining a true complementary function.

Dual mode video tracker

Target or scene tracking capability is provided by a dual mode video tracker which includes both a correlation processor (30) and a centroid processor (32) for processing incoming video signals representing the target scene (20) and for generating tracking error signals over an entire video frame or a selected mode thereof. A microcomputer (26) controls the operation of the correlation and centroid processors, as well as a preprocessor (28) which preconditions the incoming video signals. The tracker operates in any of several modes in which the correlation and centroid processors function either independently or cooperatively with each other. The correlation processor generates a reference map in pixel format which is used to produce azimuth and elevation optimal weighting values for each pixel in the field-of-view. The reference map is recursively updated. The track gate for the correlation processor is automatically sized using a gradient function derived from the optimal weighting values. The gradient function is also employed along with difference video to determine correlation tracking status. The correlation and centroid tracking errors may be combined to form a composite signal defining a true complementary function.

A reactionless drive system is disclosed comprising in combination a base, a torquer mechanism, the stator portion of which is affixed to the counter-rotational inertia member and accepting control signals from sources external to the system. A rotatable member, coupled to the torquer, is driven in a first direction. A torque compensator consisting of stator and rotor members is coupled between the base and the first mentioned rotatable member in one instance, and to an oppositely rotating member in another instance. All the foregoing components act together to maintain angular momentum of the system during its operative mode to a value of substantially zero. An electronic subsystem is provided which senses the angular velocities of the rotating members and provides a feedback signal to the torque compensator.

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Rancho Palos Verdes, CA, United States of America

Arthur K Rue