Deployable, forward looking range sensor for command detonation

• US 10,533,831 B1
• Filed: 09/06/2018
• Issued: 01/14/2020
• Est. Priority Date: 09/06/2018
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Choiniere, Michael J., Stockwell, Jason T.
• Primary Examiner(s): David, Michael D
• Application Number:
  US16/123,474
• Time in Patent Office: 495 Days
• CPC Class Codes: F42C 13/02 operated by intensity of light or similar radiation
• CPC Class Codes: F42C 13/023 using active distance measurement

Abstract

The system and method for accurately determining range-to-go for the time-delayed command detonation of a projectile. Using dual laser and/or radio frequency detectors on a spinning projectile to determine the range-to-go, time-to-go, or lateral offset from the projectile to the target. The detectors are forward facing and rear facing and are located in a tail kit such that cost can be greatly reduced on a spinning projectile. The deployable detector(s) may be a light pipe, mirrors, or the like and comprise APD or PIN diodes.

Claims

1. A method for guiding a projectile to a target, comprising:

providing a projectile comprising a tail portion and a nose portion, wherein the tail portion is rotatable along a longitudinal axis of the projectile independently from the nose portion;

detecting a first laser signal via a rear facing detector mounted on the tail end of the projectile;

determining a first time at which the first laser signal is detected via the rear facing detector;

detecting a reflected laser signal via a forward facing detector mounted on the tail portion of the projectile, the reflected laser signal being the reflected laser signal off the target;

determining a second time at which the reflected laser signal is detected via the forward facing detector of the projectile;

comparing the first time to the second time to determine a time delay;

determining a lateral offset between the projectile and the target using the time delay between detection by the rear facing detector and detection by the forward facing detector and a speed of the projectile; and

calculating an optimum time for detonation of the projectile using a Kaman filter.

2. The method for guiding a projectile according to claim 1, further comprising sending a signal to detonate the projectile at the optimum time.

3. The method for guiding a projectile according to claim 1, wherein the rear facing detector of the projectile is an electro-optical PIN diode.

4. The method for guiding a projectile according to claim 1, wherein the forward facing detector of the projectile is an array PIN diode.

5. The method for guiding a projectile according to claim 1, wherein a range finding clock is started when the first signal is detected (T_zero) by the rear facing detector and the range finding clock is stopped when the second signal is detected by the forward facing detector (T_reflected), thereby creating a time differential that represents a round trip time between the projectile and the target which can be converted to a range-to-go.

6. The method for guiding a projectile according to claim 5, wherein a time to detonation clock is started when a signal is detected by the forward facing front detector on the projectile at a time (T_start) when an angle, theta, is approaching perpendicular to the projectile'"'"'s direction of travel to the reflected signal off the target.

7. The method for guiding a projectile according to claim 6, wherein the time to detonation clock is stopped and the projectile is detonated at a time point (T_det) representing when the projectile is some distance within an interior of the target.

8. The method for guiding a projectile according to claim 7, wherein determining the detonation time point (T_det) is dependent on at least one of the projectile speed, the type of structure, and the particular projectile.

9. The method for guiding a projectile according to claim 7, wherein the detonation time point (T_det) is programmed at the time of launch.

10. The method for guiding a projectile according to claim 1, wherein the first laser signal further comprises a first pulse repetition interval and the reflected laser signal further comprises a second pulse repetition interval.

11. The method for guiding a projectile according to claim 10, wherein the lateral offset between the projectile'"'"'s trajectory and the target'"'"'s actual position is determined by measuring a time expansion between the first pulse repetition interval and the second pulse repetition interval and convolving the projectile'"'"'s velocity with the time-to-go thereby improving an accuracy of a detonation.

12. A method for guiding a projectile, comprising:

providing a projectile comprising a tail portion and a nose portion, wherein the tail portion is rotatable along a longitudinal axis of the projectile independently from the nose portion;

detecting a first radio frequency (RF) signal via a rear facing detector mounted on the tail of the projectile;

determining a first time at which the first RF signal is detected via the rear facing detector of the projectile;

detecting a second RF signal via a forward facing detector mounted on the tail of the projectile, the second RF signal at least partially being the first RF signal that has reflected off a target;

determining a second time at which the second RF signal is detected via the forward facing detector of the projectile;

comparing the first time to the second time to determine a time delay;

determining a lateral offset between the projectile and the target using the time delay between detection by the rear facing detector and detection by the forward facing detector and a speed of the projectile; and

calculating an optimum time for detonation of the projectile using a Kaman filter.

13. The method for guiding a projectile according to claim 12, wherein the rear facing detector of the projectile is an end-fire array.

14. The method for guiding a projectile according to claim 12, wherein the forward facing detector of the projectile is an end-fire array.

15. The method for guiding a projectile according to claim 12, wherein the first signal further comprises a first pulse repetition interval and the second signal further comprises a second pulse repetition interval.

16. The method for guiding a projectile according to claim 15, wherein the lateral offset between the projectile'"'"'s trajectory and the target'"'"'s actual position is determined by measuring a time expansion between the first pulse repetition interval and the second pulse repetition interval and convolving the projectile'"'"'s velocity with the time-to-go thereby improving an accuracy of a detonation.

17. A guided projectile, comprising;

a tail portion and a nose portion, wherein the tail portion is rotatable along a longitudinal axis of the projectile independently from the nose portion;

a rear facing detector located on the tail portion of the guided projectile for detecting a laser or radio frequency signal, wherein the laser or radio frequency signal is from a fire control system;

a forward facing detector located on the tail portion of the guided projectile and detecting a reflected laser or radio frequency signal from a target;

a computer readable storage device having instructions, which when executed by a processor, cause the processor to execute;

determining a first time at which the laser or radio frequency signal is detected via the rear facing detector;

determining a second time at which the reflected laser or radio frequency signal is detected via the forward facing detector;

comparing the first time to the second time to determine a time delay;

determining an azimuth and an elevation of the guided projectile based on the detected laser or radio frequency signal by the rear facing detector;

determining one or more of the following using the time delay between detection by the rear facing detector and detection by the forward facing detector;

a lateral offset between the projectile and the target;

a time-to-go for the projectile to reach the target; and

a range-to-go for the projectile to reach the target; and

calculating an optimum time for detonation of the projectile using a Kaman filter.

18. The guided projectile according to claim 17, wherein instructions cause the processor to further execute:

sending a signal to detonate the guided projectile at the optimum time.