Counterbalanced rotation rate sensor

• US 6,357,295 B1
• Filed: 07/28/2000
• Issued: 03/19/2002
• Est. Priority Date: 07/28/2000
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Litton Systems Incorporated (Northrop Grumman Corporation)
• Inventors: Wyse, Stanley F.
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/628,217
• Time in Patent Office: 599 Days
• Field of Search: 735/040.2, 735/040.3, 735/040.4, 735/041.2, 735/041.3
• US Class Current: 73/504.04
• CPC Class Codes: G01C 19/00 Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

A sensor for measuring rotation rate with respect to three axes and linear acceleration with respect to two axes. Electromagnets comprising cores of high magnetic permeability and windings are fixed to structures that protrude inwardly from outer frames of upper and lower rotor assemblies. An element of high magnetic permeability is fixed to the facing surface of a rotor arm to create electromagnetic drives for counteroscillation of upper and lower sets of rotor arms. Accelerometers are horizontally aligned and fixed to the top surfaces of preselected rotor arms of the upper rotor assembly and to the bottom surfaces of aligned rotor arms of the lower set of rotor arms for measuring rotation rate with respect the x and y axes and linear acceleration with respect to the z axis. The two sets of rotor arms are connected by a torsion bar. A pair of accelerometers is each vertically aligned and fixed to the ends of aligned rotor arms of a rotor assembly for measuring rotation rate with respect to the z axis and linear acceleration with respect to the y axis. Each rotor assembly, comprising a central hub from which a set of four rotor arms radiate and a surrounding outer frame connected to the hub through a plurality of vanes, is formed of a single integral piece.

Claims

1. A sensor comprising, in combination:

a) a first rotor and a second rotor, each of said rotors including a plurality of radially-directed rotor arms that extend from a central hub;

b) each of said rotors being received within an associated frame;

c) a plurality of vanes connecting each of said hubs to said associated frames;

d) a torsion spring being fixed to said hubs;

e) each of said rotor arms comprising parallel upper and lower, radially-directed planar surfaces and an orthogonal end surface;

f) at least one accelerometer fixed to at least one of said upper, lower and end surfaces; and

g) said rotors being driven to counteroscillate about said torsion spring.

2. A sensor as defined in claim 1 further including:

a) an electromagnet fixed to the interior of each of said frames;

b) one of said rotor arms of each of said rotors including a region of magnetic composition; and

c) each of said rotors and associated frames being arranged so that a region of magnetic composition is adjacent an electromagnet.

3. A sensor as defined in claim 2 further characterized in that:

a) each of said frames is generally annular;

b) each of said frames includes an inwardly-directed region; and

c) an electromagnet is fixed to said inwardly-directed region.

4. A sensor as defined in claim 3 wherein said region of magnetic composition comprises a substantially planar element of high magnetic permeability.

5. A sensor as defined in claim 4 wherein said substantially-planar element of high magnetic permeability faces an electromagnet.

6. A sensor as defined in claim 5 wherein said facing surface of said substantially-planar element of high magnetic permeability is radially-directed.

7. A sensor as defined in claim 6 wherein said substantially-planar element of high magnetic permeability comprises ferrite.

8. A sensor as defined in claim 1 wherein each of said rotors, associated vanes and frame comprises a distinct integral unit.

9. A sensor as defined in claim 8 wherein each said of said distinct integral structures comprises titanium.

10. A sensor as defined in claim 1 wherein said torsion spring includes a central torsion bar and opposed anchor ends for engaging said hubs.

11. A sensor as defined in claim 10 wherein each of said anchor ends is of greater cross sectional area than said torsion bar.

12. A sensor as defined in claim 11 wherein said torsion spring comprises an integral element.

13. A sensor as defined in claim 12 wherein said end anchors are fixed to said hubs by mean of adhesive.

14. A sensor as defined in claim 13 wherein said adhesive is EPOXY.

15. A sensor comprising, in combination:

a) a first rotor and a second rotor, each of said rotors including a plurality of radially-directed rotor arms that extend from a central hub;

b) each of said rotors being received within an associated frame;

c) a plurality of vanes connecting each of said hubs to said associated frames;

d) a torsion spring being fixed to said hubs;

e) an electromagnet fixed to the interior of each of said frames;

f) one of said rotor arms of each of said rotors including a region of magnetic composition;

g) each of said rotors and associated frames being arranged so that a region of magnetic composition is adjacent an electromagnet; and

h) at least one accelerometer fixed to at least one of said rotor arms.

16. A sensor as defined in claim 15 further characterized in that:

a) each of said frames is generally annular;

b) each of said frames includes an inwardly-directed region; and

c) an electromagnet is fixed to said inwardly-directed region.

17. A sensor as defined in claim 15 wherein said region of magnetic composition comprises a substantially planar element of high magnetic permeability.

18. A sensor as defined in claim 17 wherein said substantially-planar element of high magnetic permeability faces an electromagnet.

19. A sensor as defined in claim 18 wherein said facing surface of said substantially-planar element of high magnetic permeability is radially-directed.

20. A sensor as defined in claim 19 wherein said substantially-planar element of high magnetic permeability comprises ferrite.

21. A sensor as defined in claim 15 further characterized in that:

a) each of said rotor arms comprises parallel upper and lower, radially-directed planar surfaces and an orthogonal end surface; and

b) said at least one accelerometer being fixed to at least one of said upper, lower and end surfaces.

22. A sensor comprising, in combination:

a) a first rotor and a second rotor, each of said rotors being substantially planar and including a plurality of radially-directed rotor arms that extend from a central hub;

b) said rotors being received within a frame;

c) a plurality of vanes connecting each of said hubs to said frame so that said rotors are substantially parallel to one another;

d) a torsion spring being fixed to said hubs;

e) each of said rotor arms comprising parallel upper and lower radially-directed planar surfaces; and

f) at least one accelerometer fixed to at least one of said upper, lower and end surfaces.

23. A sensor as defined in claim 22 further including:

a) a pair of electromagnets fixed to the interior of said frame;

b) one of said rotor arms of each of said rotors including a region of magnetic composition; and

c) each of said rotors being arranged so that a region of magnetic composition is adjacent each of said electromagnets.

24. A sensor as defined in claim 23 further characterized in that:

a) said frame is generally annular and includes a pair of inwardly-directed regions; and

b) an electromagnet is fixed to each of said inwardly-directed regions.

25. A sensor as defined in claim 24 wherein each of said regions of magnetic composition comprises a substantially planar element of high magnetic permeability.

26. A sensor as defined in claim 25 wherein each of said substantially-planar elements of high magnetic permeability faces an electromagnet.

27. A sensor as defined in claim 26 wherein said facing surface of said substantially-planar element of high magnetic permeability is radially-directed.

28. A sensor as defined in claim 27 wherein said substantially-planar element of high magnetic permeability comprises ferrite.

29. A sensor as defined in claim 22 wherein said rotors, associated vanes and frame comprises an integral unit.

30. A sensor as defined in claim 29 wherein said integral unit comprises titanium.

31. A sensor as defined in claim 22 wherein said torsion spring includes a central torsion bar and opposed anchor ends for engaging said hubs.

32. A sensor as defined in claim 31 wherein each of said anchor ends is of greater cross sectional area than said torsion bar.

33. A sensor as defined in claim 32 wherein said torsion spring comprises an integral element.

34. A sensor as defined in claim 33 wherein said end anchors are fixed to said hubs by means of adhesive.

35. A sensor as defined in claim 34 wherein said adhesive is EPOXY.

36. A sensor comprising, in combination:

a) a first rotor and a second rotor, each of said rotors being substantially planar and including a plurality of radially-directed rotor arms that extend from a central hub;

b) said rotors being received within a frame;

c) a plurality of vanes connecting each of said hubs to said frame so that said rotors are substantially parallel to one another;

d) a torsion spring being fixed to said hubs;

e) a pair of electromagnets fixed to the interior of said frame;

f) one of said rotor arms of each of said rotors including a region of magnetic composition;

g) each of said rotors being arranged so that a region of magnetic composition is adjacent each of said electromagnets; and

h) at least one of accelerometer fixed to at least one of said rotor arms.

37. A sensor as defined in claim 36 further characterized in that:

a) said frame is generally annular and includes a pair of inwardly-directed regions; and

b) an electromagnet is fixed to each of said inwardly-directed regions.

38. A sensor as defined in claim 37 wherein each of said regions of magnetic composition comprises a substantially planar element of high magnetic permeability.

39. A sensor as defined in claim 38 wherein each of said substantially-planar elements of high magnetic permeability faces an electromagnet.

40. A sensor as defined in claim 39 wherein said facing surface of said substantially-planar element of high magnetic permeability is radially-directed.

41. A sensor as defined in claim 40 wherein said substantially-planar element of high magnetic permeability comprises ferrite.

42. A sensor as defined in claim 36 further including:

a) each of said rotor arms comprising parallel upper and lower radially-directed planar surfaces; and

b) at least one accelerometer fixed to at least one of said upper, lower and end surfaces.