Device for the unambiguous measurement of the roll of a projectile and application to the correction of the path of a projectile

• US 6,483,455 B2
• Filed: 12/06/2000
• Issued: 11/19/2002
• Est. Priority Date: 12/15/1999
• Status: Expired due to Fees

• Current Assignee: Thomson-CSF
• Original Assignee: Thomson-CSF
• Inventors: Fleury, Sylvie, Beaulieu, Louis
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/729,837
• Publication Number:
  US 20010004247A1
• Time in Patent Office: 713 Days
• Field of Search: 342/5, 342/6, 342/7, 342/61, 342/62, 342/104, 342/105, 342/175, 342/188, 342/195, 244/3.1, 244/3.11, 244/3.21, 244/3.22, 244/3.23, 244/3.14, 244/3.12, 244/3.13
• US Class Current: 342/62
• CPC Class Codes: F41G 7/305 for spin-stabilized missiles
• CPC Class Codes: G01S 13/883 for missile homing, autodirectors missile guidance systems F41G7/22
• CPC Class Codes: G01S 7/025 involving the transmission of linearly polarised waves

Abstract

A device for the unambiguous measurement of the angle of roll of a projectile, comprises at least a radar equipped with means of processing and sending a signal to the casing of the projectile in at least one direction of incident polarization; a set of parallel grooves made on the casing, the depth of which is modulated dissymmetrically with respect to the axis of symmetry of the projectile; the axis of symmetry of the projectile not passing through the point of the antenna of the radar where the antenna beam is generated, the processing means analyzing, in reception, a signal back-scattered by the casing of the projectile, the signal being modulated as a function of the angle of roll of the projectile, the modulation having two maximum local values corresponding to two angular roll positions of the projectile such that the polarization {overscore (E)} is parallel to the grooves, the processing means removing the 180° ambiguity by comparing the levels of the local maximum values. The device can be applied especially to the correction of the paths of projectiles fired by a gun and when the correction requires knowledge of the roll position of the projectiles.

Claims

1. A device for measurement of angle of roll of a projectile, comprising:

a radar equipped with means of processing and sending a signal to a casing of the projectile in at least one direction of incident polarization; and

a set of parallel grooves made on the casing having depths modulated dissymmetrically with respect to an axis of symmetry of the projectile;

the axis of symmetry of the projectile not passing through a point of an antenna of the radar where the antenna beam is generated; and

wherein the processing means is configured for analyzing, in reception, a signal back-scattered by the casing of the projectile, the signal being modulated as a function of the angle of roll of the projectile, the modulation having two maximum local values corresponding to two angular roll positions of the projectile such that the polarization is parallel to the grooves, the processing means removing a 180°

ambiguity by comparing levels of the local maximum values.

2. A device according to claim 1, wherein the depth of the grooves increases from one peripheral groove to another peripheral groove.

3. A device according to claim 2, wherein the depth of the grooves increases linearly.

4. A device according to claim 1, wherein a reference angle of roll corresponds to the maximum value with a highest of the levels.

5. A device according to claim 4, wherein the reference angle is taken to be a starting angle 0°

.

6. A device according to claim 1, wherein the signal received is analyzed according to two orthogonal polarizations.

7. A device according to claim 1, wherein the grooves are machined on the casing.

8. A device according to claim 1, further comprising a means for providing a correction path of the projectile, wherein the projectile further comprises:

a side impeller, wherein the impeller is controlled as a function of the angle of roll measured by the device;

wherein the grooves are modulated in depth on a casing of the projectile.

9. A radar system for measuring an angle of roll of a projectile, the radar system comprising:

a radar transmitter for transmitting a radar signal according to a given polarization, the radar signal being directed to illuminate at least a portion of the projectile having a signature which varies with the angle of roll of the projectile;

a radar receiver for receiving a return signal back-scattered from the projectile, the return signal being modulated by the portion of the projectile as a function of the angle of roll of the projectile to have two maximum local values respectively corresponding to two positions of the angle of roll of the projectile; and

a radar processor for analyzing the return signal and determining the angle of roll of the projectile based on levels of the two maximum local values.

10. A radar system according to claim 9, wherein the radar processor removes a 180°

ambiguity by comparing the levels of the two maximum local values.

11. A radar system according to claim 9, wherein the portion of the projectile having a signature which varies with the angle of roll comprises:

a set of parallel grooves on a casing of the projectile, wherein depths of respective ones of the set of parallel grooves are modulated dissymmetrically with respect to an axis of symmetry of the projectile.

12. A radar system according to claim 11, wherein a first peripheral groove of the set of parallel grooves has a minimum depth and a second peripheral groove opposite the first peripheral groove has a maximum depth and the depths of adjacent ones of the set of parallel grooves increases from the first peripheral groove to the second peripheral groove.

13. A radar system according to claim 11, wherein the set of parallel grooves are machined on the casing.

14. A radar system according to claim 9, wherein the projectile further comprises:

a side impeller configured to be controlled as a function of the angle of roll of the projectile determined by the radar processing means.

15. A method of measuring an angle of roll of a projectile using a radar system, the method comprising:

transmitting, from the radar system, a radar signal with a given polarization to illuminate at least a portion of the projectile, wherein the projectile has a signature which varies with the angle of roll of the projectile;

receiving, at the radar system, a return signal back-scattered from the projectile, the return signal being modulated by the portion of the projectile as a function of the angle of roll of the projectile to have two maximum local values respectively corresponding to two positions of the angle of roll of the projectile; and

processing the return signal to determine the angle of roll of the projectile based on levels of the two maximum local values.

16. A method according to claim 15, further comprising:

comparing the levels of the two maximum local values to remove a 180°

ambiguity.

17. A method according to claim 15, further comprising:

providing, on a casing of the projectile, a set of parallel grooves on of the projectile, wherein depths of respective ones of the set of parallel grooves are modulated dissymmetrically with respect to an axis of symmetry of the projectile.

18. A method according to claim 17, wherein a first peripheral groove of the set of parallel grooves has a minimum depth and a second peripheral groove opposite the first peripheral groove has a maximum depth and the depths of adjacent ones of the set of parallel grooves increases from the first peripheral groove to the second peripheral groove.

19. A method according to claim 17, further comprising:

machining the set of parallel grooves on the casing.

20. A method according to claim 15, further comprising:

controlling the projectile using a side impeller, the projectile being controlled as a function of the angle of roll of the projectile determined by the radar processing means.