# US 4,378,918 A · Quasi-stabilization for line of sight guided missiles

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- Number: US 4,378,918 A
- Document ID: US4378918A
- Status: Granted
- Kind: A
- Application number: 06/223,863
- Filed: 1981-01-09
- Granted: 1983-04-05
- Earliest claimed: 1981-01-09
- Assignees: The United States of America as represented by the Secretary of the Army
- Inventors: Walter E. Miller, Jr.; James W. McKelvy
- Web page: https://patentgrep.com/patent/US4378918A

## CPC

- F41G 7/24: Beam riding guidance systems (conical-scan beam beacons therefor G01S1/42)
- F41G 7/30: Command link guidance systems {(homing F41G7/2206)}
- F41G: WEAPON SIGHTS; AIMING (optical aspects thereof G02B)

## Abstract

An open loop reduction in gunner aiming error is provided by a rate gyro dback to the missile command electronics. The low frequency movements are filtered out of the feedback circuit; permitting tracking of low frequency crossing targets, while eliminating higher frequency gunner jitter inputs.

## Claims

### Claim 1

In a system wherein a sighting device is aimed with unwanted angle jitter at a target, a missile is guided towards said target along a boresight of said sighting device by a control device which sends guided control signals to said missile to bring said missile into the boresight line of said sighting device, the improvement comprising a gyro mounted to a chassis and having an output signal at its output which is a measure of movement of said chassis; a bandpass filter having an input and an output; the output signal of said gyro being connected to the input of said bandpass filter; the output of said bandpass filter being connected to said control device so as to subtract the signal output of the bandpass filter from the guided control signals to be sent to said missile; said bandpass filter blocks the passing of low frequency signals from the output signal of said gyro such as those produced in tracking a target; said bandpass filter further blocking high frequency output signals from said gyro such as those generated by electronic noise; and said bandpass filter allowing to pass signals from said gyro which are in the angle jitter frequency range so as to eliminate from the guidance of the missile most unwanted angle jitter input.

### Claim 2 (depends on 1)

A system as set forth in claim 1 wherein said gyro is a position gyro.

### Claim 3 (depends on 1)

A system as set forth in claim 1 wherein said gyro is a rate gyro.

### Claim 4 (depends on 1, 3)

A system as set forth in claim 1 or claim 3 further comprising an integrator connected between said gyro and said bandpass filter.

### Claim 5 (depends on 4)

A system as set forth in claim 4 further comprising a missile tracker device mounted to said chassis which produces an error signal in accordance with said missiles' deviation from said boresight; a subtractor having first and second inputs and an output; said first input of said subtractor being connected to receive error signal from said tracker device; said second input of the subtractor being connected to the output of said bandpass filter so as to subtract the output signal from the bandpass filter from that of the tracker device; and the output of the subtractor being connected to said control device so as to provide guidance control signals which will command the missile to correct its error position with respect to said boresight, having had some unwanted chassis jitter removed as a system error source.

### Claim 6 (depends on 5)

A system as set forth in claim 5, further comprising an adder having first and second inputs and an output; the output of said control device being connected to said first input of the adder; the output of said adder providing the guidance control signals; a low pass filter being connected between the output of said gyro and the second input of said adder whereby low frequencies such as those produced by the tracking of a crossing target will be added as a crossing rate bias to the guidance control signals.