Aircraft automatic boresight correction

• US 4,698,489 A
• Filed: 11/15/1985
• Issued: 10/06/1987
• Est. Priority Date: 09/30/1982
• Status: Expired due to Fees

• Current Assignee: BAE Systems Controls Incorporated (BAE Systems Plc)
• Original Assignee: General Electric Company
• Inventors: Tye, Gene, Hickin, Charles W. R.
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US06/798,535
• Time in Patent Office: 690 Days
• Field of Search: 235/400, 235/404, 235/407, 235/410, 235/411, 235/412, 364/423, 89/41 ME, 89/41 MA, 89/41.05, 89/41.06, 89/41.14, 89/41.17, 89/41.19, 89/41.21, 434/14.20, 434/22
• US Class Current: 235/407
• CPC Class Codes: F41G 3/142 based on observation of a first shoot; using a simulated shoot training F41G3/26
• CPC Class Codes: F41G 3/22 for vehicle-borne armament, e.g. on aircraft
• CPC Class Codes: F41G 3/323 for checking the angle between the muzzle axis of the gun and a reference axis, e.g. the axis of the associated sighting device testing alignment of axes in general G01B11/27
• CPC Class Codes: F41G 5/18 Tracking systems for guns on aircraft

Abstract

A boresight correction system is disclosed that determines the existing error between an aircraft gunsight and its gun systems while prescribed aircraft maneuvers are performed and which automatically corrects the gunsight system to compensate for this error. The system includes a sensor for detecting bullet positions, hardware that determines the bullet positions relative to the gun boresight, a digital processor to determine the above mentioned error, and to correct the gunsight system according to this error, and a non-volatile memory in the digital processor to store a corrected boresight position.

Claims

1. An automatic boresight correction system for use in an aircraft having a gunnery system and a sighting system therefor, comprising:

a head-up display for displaying a boresight symbol through said sighting system, said boresight symbol representing a reference point for the prediction for the instantaneous positions of bullets fired from said gunnery system;

a video sensor for producing a sequence of video signals representing the instantaneous positions of said bullets;

a display processor for generating positioning data for said boresight symbol, said display processor including a video processing section, means for coupling video signals to said processing section for processing and storing the video signals representative of the relative positions of said bullets and said boresight signal as detected by said video sensor;

said display processor further including a boresight symbol generator;

means for coupling the boresight symbol positioning data generated by said display processor to said boresight symbol generator to position said boresight symbol in response thereto;

means for actuating said boresight system; and

a digital processor in said display processor responsive to said actuating means for predicting the instantaneous positions of said bullets and for computing any error between said predicted and the instantaneous bullet positions sensed by said video sensor, said digital processor being further adapted to adjust the position of said boresight symbol data to compensate for said computed error.

2. The correction system of claim 1 wherein said digital processor includes a non-volatile memory for storing the adjusted position data for said boresight symbol.

3. The correction system of claim 1 wherein said digital processor is additionally responsive to the adjusted position data of said boresight symbol to perform weapon delivery computations for said gunnery system.

4. The correction system of claim 1 wherein said digital processor is additionally responsive to said computed error to perform weapon delivery computations for said gunnery system.

5. The correction system of claim 1 wherein said aircraft includes sensors for providing data to said digital processor representative of the instantaneous motion of said aircraft, said digital processor being responsive to said motion data for factoring said motion data into the computation of said predicted instantaneous bullet positions.

6. The correction system of claim 1 wherein said video sensor comprises a cockpit television camera, said camera including means for delivering a signal to said videa processing section representing bullet positions and said boresight symbol position on said head-up display.

7. The correction system of claim 6 wherein said video processing section includes means for extracting and separating the signals representing the positions of said boresight symbol and of said bullets from the received camera signal.

8. The correction system of claim 7 wherein said video processing section includes means for providing a predetermined electronic window substantially centered around said predicted instantaneous bullet positions, said window excluding the portions of said camera signal outside the window bounds;

whereby the time and memory required by said video processing section and said digital processor for processing said received camera signal are reduced.

9. The correction system of claim 1 wherein at least some of said bullets are tracer rounds optically detectable by said video sensor.

10. A method for boresighting a gunnery system in an aircraft having a sighting system including a boresight symbol, comprising the steps of:

firing several rounds from said gunnery system;

detecting the actual positions of said fired rounds relative to said boresight symbol;

predicting the position of said fired rounds relative to said boresight symbol;

computing an error vector representative of the difference between the predicted positions and the actual positions of said fired rounds; and

correcting said sighting system to compensate for said difference according to said error vector.

11. The method of claim 10 wherein the step of predicting the positions of said fired rounds includes factoring in data representative of the instanteous motion of said aircraft.

12. The method of claim 11 wherein the step of detecting the actual positions of said fired rounds includes computing the centroid of a plurality of said fired rounds;

and the step of computing said error vector includes comparing said computed centroid with a predicted centroid computed relative to said boresight symbol.

13. The method of claim 12 wherein the step of comparing said computed centroid further includes:

performing a comparison for each of a plurality of instantaneous positions of said computed centroid to the respective instantaneous predicted centroid positions.

14. The method of claim 13 wherein the step of correcting said sighting system further includes:

averaging said comparisons for said plurality of instantaneous positions; and

moving the position of said boresight symbol in a direction adapted to reduce said error vector by an amount proportional to the average of said comparisons.

15. A method for automatically boresighting a gunnery system in an aircraft having a sighting system including a bore sight symbol comprising the steps of:

firing several rounds from said gunnnery system;

detecting the actual positions of said fired rounds relative to said bore sight symbol;

computing a predicted trajectory of said fired rounds relative to said bore sight signal;

computing an error vector representative of the difference between predicted positions and the actual positions of said fired rounds; and

correcting said sighting systems to compensate for said difference according to said error vector.

16. The method of claim 15 wherein said aircraft is in flight and the step of detecting said actual trajectory of said fired rounds includes:

detecting the individual position of each fired round;

computing the centroid of a plurality of individual rounds;

computing the trajectory of said centroid; and

comparing said computed trajectory of said centroid with said predicted trajectory computed relative to said boresight symbol.

17. The method of claim 16 wherein the step of computing the predicted trajectory of said fired rounds includes factoring in data representative of the instantaneous motion of said aircraft.

18. The method of claim 15 wherein said aircraft is in flight and the step of determining said error vector includes:

performing a series of in-flight iterative solutions, each solution determining a corresponding component of said error vector by comparing the actual trajectory to said predicted trajectory.

19. The method of claim 18 wherein the step of computing the predicted trajectory of said fired rounds includes factoring in data representative of the instantaneous motion of said aircraft.

20. The method of claim 19 wherein the step of correcting said sighting system includes:

moving the position of said boresight symbol in a direction to reduce said error vector by an amount proportional to the corresponding error vector component for each iterative solution.

21. The method of claim 19 wherein the step of computing the predicted trajectory of said fired rounds includes factoring in data representative of the instantaneous motion of said aircraft.

22. The method of claim 21 wherein the step of correcting said sighting system includes moving the position of said boresight symbol in a direction adapted to reduce said error vector by an amount proportional to each error vector component.

23. The method of claim 15 wherein the step of firing several rounds includes firing several tracer bullets to facilitate the detection of said fired rounds.

24. The method of claim 15 wherein said aircraft is in flight and the step of computing said error vector includes:

performing a first constant turn maneuver in one direction;

computing a first error component based on said first turn maneuver;

performing a second constant turn maneuver approximately perpendicular to said first turn manuever;

computing a second error component based on said second turn maneuver; and

combining said first and second components to provide said error vector.