Gimbaled scanning system and method

• US 6,576,891 B2
• Filed: 02/16/2001
• Issued: 06/10/2003
• Est. Priority Date: 02/16/2001
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Ansley, David A.
• Primary Examiner(s): Pyo, Kevin
• Assistant Examiner(s): Sohn, Seung C.
• Application Number:
  US09/785,150
• Publication Number:
  US 20020139926A1
• Time in Patent Office: 844 Days
• Field of Search: 250/234, 250/235, 250/236, 250/203.1, 250/206.2, 359/197-198, 359/212-221, 359/554-555, 359/876, 359/872, 280/764.1, 352/132, 296/223-224, 396/13, 396/12, 396/7
• US Class Current: 250/234
• CPC Class Codes: H04N 3/08 having a moving reflector

Abstract

A scanning system (10) and a method permit scanning a desired field-of-view within a maximized field-of-regard at a constant speed without reversing the scan direction about a primary axis (38). The system includes a mirror (20) which rotates about the primary axis (38). The mirror (20) is supported for rotation about a flip axis (40) which is perpendicular to the primary axis (38). Rotation of the mirror (20) about the primary axis (38) is divided into a scan period during which the field-of-view is scanned by the mirror (20), and a flip period during which the mirror (20) rotates about the flip axis (40). The mirror (20) is mounted in a gimbal for independent rotation about a secondary axis (24) which is parallel to the primary axis (38). Rotation of the mirror (20) about the secondary axis (24) provides an adjustment of the mirror orientation such that at the end of the scan period the mirror (20) faces the end of the field-of-view, and at the end of the flip period the mirror (20) faces the beginning of the field-of-view.

Claims

1. A system for scanning at least a portion of a field-of-regard, comprising:

means for sensing an image, and means for directing the image from the field-of-regard to the means for sensing, the means for directing including a reflecting surface that is rotatable about a central axis, an adjustment axis in a plane parallel to the central axis, an elevation axis transverse to the adjustment axis and a flip axis perpendicular to the central axis.

2. A system as set forth in claim 1, wherein the elevation axis is perpendicular to the adjustment axis.

3. A system as set forth in claim 1, wherein the means for sensing includes a sensor package.

4. A system as set forth in claim 1, wherein the reflecting surface is a mirror.

5. A system as set forth in claim 1, further comprising a support structure for supporting the reflecting surface at an elevated position.

6. A system as set forth in claim 5, wherein the support structure includes a vehicle having a mast and the reflecting surface is mounted at an elevated position with the central axis generally extending along the mast.

7. A system as set forth in claim 1, wherein the reflecting surface rotates in a constant direction about the central axis.

8. A system as set forth in claim 1, further comprising a housing having a turret portion through which the central axis passes that rotates about the central axis and a sight portion mounted to the turret portion that is selectively rotatable relative to the turret portion about the flip axis.

9. A system as set forth in claim 8, wherein the reflecting surface is mounted on a gimbal that extends within the sight portion.

10. A system as set forth in claim 9, wherein the gimbal includes portions that are independently and selectively rotatable about an elevation axis and an adjustment axis that is perpendicular to the elevation axis.

11. A combination comprising a vehicle having a mast;

a housing mounted to the mast; and

a scanning system including both a sensor package and a reflecting surface that directs an image from at least a portion of a field-of-regard to the sensor package, wherein the housing includes a turret portion that rotates about a primary axis that passes through the turret portion and a sight portion connected to the turret portion for selective rotation about a flip axis in a plane that is perpendicular to the primary axis, and the reflecting surface is mounted in the sight portion of the housing, the reflecting surface being independently rotatable about an adjustment axis in a plane parallel to the primary axis and an elevation axis transverse to the adjustment axis.

12. A combination as set forth in claim 11, wherein the primary axis is substantially aligned with a longitudinal axis of the mast.

13. A system for scanning at least a portion of a field-of-regard, comprising a housing, a sensor package, and a reflecting surface contained in the housing for directing an image from the field-of-regard to the sensor package, at least a portion of the housing being rotatable about a central axis that passes through the housing, the reflecting surface being rotatable about the central axis, an adjustment axis that passes through the housing and is in a plane that is parallel to the central axis, a flip axis that is perpendicular to the central axis, and an elevation axis that is perpendicular to the adjustment axis.

14. A system as set forth in claim 13, wherein the housing includes a turret portion through which the central axis passes, and a sight portion containing the reflecting surface and through which the adjustment axis passes.

15. A system as set forth in claim 14, wherein the sight portion is selectively rotatable about the flip axis.

16. A method for scanning at least a portion of a field-of-regard, comprising:

providing a scanning system that includes a sensor package, a housing having a turret portion that rotates about a central axis which passes through the turret portion and a sight portion mounted to the turret portion that is selectively rotatable relative to the turret portion about a flip axis in a plane that is perpendicular to the central axis, and a reflecting surface mounted in the sight portion to direct an image from the field-of-regard to the sensor package, the reflecting surface being rotatable about an adjustment axis that lies in a plane that is parallel to the central axis and an elevation axis that is perpendicular to the adjustment axis;

continuously rotating the housing about the central axis;

selectively rotating the sight portion of the housing about the flip axis during at least a portion of each revolution about the central axis; and

selectively rotating the reflecting surface about the adjustment axis and the elevation axis.

17. A method as set forth in claim 16, wherein rotating about the adjustment axis includes rotating at a rate of about thirty degrees per second.

18. A method as set forth in claim 16, further comprising rotating the sight portion of the housing about the flip axis approximately one hundred and eighty degrees during each revolution about the central axis.

19. A method as set forth in claim 16, wherein providing the scanning system includes mounting the reflecting surface on a gimbal that is mounted for rotation with the sight portion of the housing, the gimbal providing independent rotation of the reflecting surface about the adjustment axis and the elevation axis.

20. A method as set forth in claim 16, wherein rotating about the central axis includes rotating at a substantially constant speed.

21. A method as set forth in claim 16, wherein rotating about the adjustment axis includes rotating at a speed relative to the rotation about the central axis to direct images from a one hundred eighty degree field-of-view to the sensor package.

22. A method as set forth in claim 16, wherein rotating about the adjustment axis includes rotating at a rate of about six degrees per second for at least a portion of each revolution about the central axis.

23. A method as set forth in claim 16, wherein rotating about the elevation axis includes indexing the reflecting surface by incrementally rotating the reflecting surface about the elevation axis.

24. A method as set forth in claim 16, wherein rotating about the central axis includes rotating at a rate of about sixty degrees per second.

25. A method for scanning at least a portion of a field-of-regard, comprising:

providing a scanning system that includes a sensor package, a housing having a turret portion that rotates about a central axis which passes through the turret portion and a sight portion mounted to the turret portion that is selectively rotatable relative to the turret portion about a flip axis in a plane that is perpendicular to the central axis, and a reflecting surface mounted in the sight portion to direct an image from the field-of-regard to the sensor package;

continuously rotating the housing about the central axis; and

selectively rotating the sight portion of the housing about the flip axis during at least a portion of each revolution about the central axis,

wherein rotating about the central axis and rotating about the flip axis includes sequentially and repeatedly scanning through a first phase and a second phase,

the first phase including a first scan period including rotating the reflecting surface about the adjustment axis at a constant first speed through a desired field-of-view, a first flip period including rotating the sight portion of the housing about the flip axis through approximately one hundred eighty degrees while rotating the reflecting surface about the adjustment axis at a second speed greater than the first speed through a positive adjustment angle to face the reflecting surface toward a starting edge of the field-of-view at the end of the first flip period, and

the second phase including a second scan period including rotating the reflecting surface about the adjustment axis at a constant first speed through a desired field-of-view, a second flip period including rotating the sight portion of the housing about the flip axis through approximately one hundred eighty degrees while rotating the reflecting surface about the adjustment axis at a second speed greater than the first speed through a negative adjustment angle to face the reflecting surface toward a starting edge of the field-of-view at the end of the second flip period.

26. A method as set forth in claim 25, further comprising determining either the positive adjustment angle or the negative adjustment angle as a function of the duration of either the first flip period or the second flip period, respectively, the desired field of view and the speed and the direction of rotation about the central axis.

27. A method as set forth in claim 25, wherein scanning through the first phase and the second phase includes indexing the reflecting surface for elevation by rotating the reflecting surface about the elevation axis during at least one of the first and second phases.

28. A method as set forth in claim 25, wherein the method includes at least one of rotating about the central axis at a rate of about sixty degrees per second, rotating about the flip axis about one hundred eighty degrees in about half a second, rotating about the adjustment axis at a first speed of about six degrees per second, and rotating about the adjustment axis at a second speed of about thirty degrees per second.