Sanders Associates Limited

John A Smith

Ronald R Sinclair

Paul D Zemany

Theodore J Nussdorfer

Kirby A Smith

George Sebestyen

Mark A Carlson

Timothy B Sands

In a moving craft connected by a towline to an ejected and freely falling object, a brake control system determines when to engage a brake that accelerates the object to the moving craft's speed by retarding the deployment of the towline without exceeding its rated working load. The control system continually monitors the velocity and the total deployed distance of the ejected object. When a point in a velocity-distance state-space plane corresponding to the monitored velocity and the monitored total deployed distance of the ejected object has reached a switching curve (48), the control system actuates a brake (74). The switching curve (48) is the locus of intersection points (38, 40, 42, and 44) of a plurality of pairs of curves, each pair consisting of a free-fall trajectory (23, 24, 26, and 28) and a brake trajectory (30, 32, 34, and 36) and being associated with a different craft velocity. The free-fall trajectory is the trajectory that the object follows after it has been ejected from the craft and is falling away from the craft under the influence of drag. The brake trajectory is the trajectory by which the brake system causes the object to stop at the desired deployment distance.

Brake-control system for accelerating freely falling objects to a moving

A system (34) for determining deviations in the state of motion of a projectile (10) from its intended state includes a comparison module (38) that receives the outputs S of a sensor array (36). The comparison module (38) converts the sensor outputs to a measurement vector Z.sub.m and computes the deviation of this measurement vector from an intended measurement vector Z.sub.0 received from a control system. The comparison module (38) then determines the difference E.sub.Z between this measured deviation and the deviation predicted by a Kalman filter (44, 46). In generating the measurement vector Z.sub.m from the outputs of the sensor array (36), the comparison module (38) 'de-spins' the array outputs in accordance with the output of a phase reference (42), whose purpose is to indicate the phase with respect to gravity of the spin of the projectile (10) about its longitudinal axis. The Kalman filter's state-deviation estimator (46) weights the vector output of the comparison module (36) and adds it to the output of the Kalman filter's state-deviation predictor (44) to provide an updated state-deviation estimation E.sub.X (t:t), which the state-deviation predictor (44) then uses as a basis for its next cycle. The output of the comparison module (38) constitutes a measure of the performance of the state-deviation predictor (44) and is used as a correction factor for the phase reference (42) so that the system acts as a phase-locked loop to lock the phase reference (42) onto the projectile spin without the need for an external sensor to determine the direction of gravity.

State-deviation-estimation circuit employing a phase-locked-loop phase

Guidance is provided for a spinning projectile by measuring the magnitude of the angle between the spinning projectile and a target. This information is processed in conjunction with a body rate sensor to deduce the angular rate of the line of sight between projectile and the target. A means is provided for reducing the line of sight angular rate to zero, thus ensuring that the projectile will intercept the target.

Guidance system for a projectile

Control is provided to conventional gun-fired projectiles by substituting for the standard fuze thereof a device comprising a canard frame and a main housing, which threads into the fuze well of the projectile, with the canard frame being rotatable with respect to the main housing and having deflectable canards thereon for providing vernier correction on the trajectory to the projectile.

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Bedford, MA, United States of America

John A Smith