Method of designing a flexure system for tuning the modal response of a decoupled micromachined gyroscope and a gyroscoped designed according to the method

• US 20030000305A1
• Filed: 06/26/2001
• Published: 01/02/2003
• Est. Priority Date: 06/26/2001
• Status: Active Grant

• Current Assignee: Nytell Software LLC (Intellectual Ventures LLC)
• Original Assignee: Irvine Sensors Corp.
• Inventors: Tracy, Michael J.
• Granted Patent: US 6,715,352 B2
• Time in Patent Office: Days
• US Class Current: 73/504.02
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

For a decoupled to gyro to have high sensitivity to angular rate, it is necessary to have the design flexibility to achieve all the critical frequencies in the design. The geometry of the gyro is first estimated and is followed by a performance analysis to maximize the gyro sensitivity. If the performance requirements cannot be met, the next iteration is started by a new estimate of the geometry. For a given design iteration, the desired modal response is implemented with a predetermined or given gyro flexure system. The flexure system disclosed here has enough independent design parameters to allow the desired modal response required for high gyro performance to be selected by independent design choice of the available geometric and configurational design parameters of the gyroscope.

Claims

1. A method of setting the drive and sense frequencies of a gyroscope having a drive mass and a sense mass coupled together by a flexure assembly comprising:

selecting a drive stiffness, K_d;

selecting geometric parameters of said flexure assembly to obtain a desired drive frequency, ω

_d;

selecting a configurational parameter of said flexure assembly to obtain a desired sense frequency, ω

_s; and

determining whether said gyroscope has obtained desired performance and size envelope characteristics.

2. The method of claim 1 further comprising repeating selecting a drive stiffness, K_d;

selecting geometric parameters of said flexure assembly to obtain a desired drive frequency, ω

_d; and

selecting a configurational parameter of said flexure assembly to obtain a desired sense frequency, ω

_s;

until it is determined that said gyroscope has obtained desired performance and size envelope characteristics.

3. The method of claim 1 where selecting geometric parameters of said flexure assembly to obtain a desired drive frequency, ω

_d, comprises selecting length and/or width of at least one individual flexure within said flexure assembly.

4. The method of claim 3 where selecting length and width of at least one individual flexure within said flexure assembly comprises selecting length and/or width of each individual flexure within said flexure assembly.

5. The method of claim 1 where selecting a configurational parameter of said flexure assembly to obtain a desired sense frequency, ω

_s, comprises selecting an orientation of at least one flexure within said flexure assembly relative to other ones of said flexures with said flexure assembly.

6. The method of claim 5 where flexures within said flexure assembly are oriented symmetrically about an axis of symmetry of said gyroscope, and where selecting an orientation of at least one flexure within said flexure assembly relative to other ones of said flexures with said flexure assembly comprises selecting one of a possible number of orientations of said at least one flexure to said axis of symmetry of said gyroscope.

7. The method of claim 1 where said flexure assembly includes at least one pair of flexures, and where selecting a configurational parameter of said flexure assembly to obtain a desired sense frequency, ω

_s, comprises selecting an angle which said pair of flexures makes to each other.

8. The method of claim 7 where said flexure assembly comprises two diametrically opposing pairs of flexures and where selecting an angle which said pair of flexures makes to each other comprises setting a dihedral angle between each of said flexures of said two diametrically opposing pairs.

9. The method of claim 1 where selecting geometric parameters of said flexure assembly to obtain a desired drive frequency, ω

_d, comprises selecting length, L, and width, w, of four flexures formed into two pairs comprising said flexure assembly, where

10. The method of claim 1 where selecting a configurational parameter of said flexure assembly to obtain a desired sense frequency, ω

_s, comprises selecting θ

in

11. The method of claim 9 where selecting a configurational parameter of said flexure assembly to obtain a desired sense frequency, ω

_s, comprises selecting θ

in

13. The improvement of claim 12 where said geometric parameters of said flexure assembly selected to obtain a desired drive frequency, ω

_d, comprise length and/or width of at least one individual flexure within said flexure assembly.

14. The improvement of claim 13 where said selected length and width of at least one individual flexure within said flexure assembly comprises a selected length and/or width of each individual flexure within said flexure assembly.

15. The improvement of claim 12 where said configurational parameter of said flexure assembly selected to obtain a desired sense frequency, ω

_s, comprises a selected orientation of at least one flexure within said flexure assembly relative to other ones of said flexures with said flexure assembly.

16. The improvement of claim 15 where flexures within said flexure assembly are oriented symmetrically about an axis of symmetry of said gyroscope, and where said a selected orientation of at least one flexure within said flexure assembly relative to other ones of said flexures with said flexure assembly comprises a selected one of a possible number of orientations of said at least one flexure to said axis of symmetry of said gyroscope.

17. The improvement of claim 12 where said flexure assembly includes at least one pair of flexures, and where said configurational parameter of said flexure assembly selected to obtain a desired sense frequency, ω

_s, comprises a selected angle which said pair of flexures makes to each other.

18. The improvement of claim 17 where said flexure assembly comprises two diametrically opposing pairs of flexures and where said angle which said pair of flexures makes to each other comprises a selected dihedral angle between each of said flexures of said two diametrically opposing pairs.

19. The improvement of claim 12 where said geometric parameters of said flexure assembly selected to obtain a desired drive frequency, ω

_d, comprises a length, L, and width, w, of four flexures formed into two pairs comprising said flexure assembly, where

20. The improvement of claim 12 where said configurational parameter of said flexure assembly selected to obtain a desired sense frequency, ω

_s, comprises a selected θ

in

21. The improvement of claim 19 where said configurational parameter of said flexure assembly selected to obtain a desired sense frequency, ω

_s, comprises a selected θ

in

12. An improvement in a gyroscope comprising:

a drive mass;

a sense mass; and

a flexure assembly coupling said drive and sense mass together;

where said drive mass has a selecting drive stiffness, K_d obtained by selecting geometric parameters of said flexure assembly to obtain a desired drive frequency, ω

_d; and

where said sense mass as a sense stiffness K_s obtained by selecting a configurational parameter of said flexure assembly to obtain a desired sense frequency, ω

_s, and where said gyroscope has obtained desired performance and size envelope characteristics by independent selection of said geometric and configurational parameters of said flexure assembly.