Microgyroscope for Determining Rotational Motions about At Least One of Three Perpendicular Spatial Axes

• US 20120055248A1
• Filed: 05/20/2010
• Published: 03/08/2012
• Est. Priority Date: 05/27/2009
• Status: Active Grant

• Current Assignee: Hanking Electronics Hongkong Company Limited
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Hammer, Hanno
• Granted Patent: US 8,904,866 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass

Abstract

A microgyroscope is used to determine rotational motions about at least one of three perpendicular spatial axes x, y, and z. The microgyroscope has a substrate (1) on which multiple masses (2x, 2y, 9) which oscillate parallel to the plane of the substrate (1) in an x-y plane are situated. Some of the oscillating masses (2x, 2y) are attached to the substrate (1) by means of springs and anchorings. Drive elements (4a, 4b) are used to maintain oscillating vibrations of the masses (2x, 2y, 9) which are subjected to Coriolis forces when the substrate (1) rotates about any given spatial axis. Sensor elements detect the deflections of the masses (2x, 2y, 9) due to the Coriolis forces generated. Some of the oscillating masses are x masses (2x) which are also deflectable along the z axis perpendicular to the substrate (1), by means of which they are able to detect yaw rates about the x axis, and/or some of the oscillating masses are y masses (2y) which are also deflectable along the z axis perpendicular to the substrate (1), by means of which they are able to detect yaw rates about the y axis, and/or others of the oscillating masses are z masses (9) which are also deflectable in the x-y plane, but perpendicular to their respective drive direction, by means of which they are able to detect yaw rates about the z axis.

Claims

1. A microgyroscope for determining rotational motions about at least one of three perpendicular spatial axes x, y, and z, comprising:

a substrate on which a plurality of masses are situated, the plurality of masses oscillating in parallel to a plane of the substrate in an x-y plane, a subset of oscillating masses in the plurality of masses being attached to the substrate by springs and anchoring;

drive elements for maintaining the oscillating vibrations for the plurality of masses which are subjected to Coriolis force when the substrate rotates about one of the three perpendicular spatial axes x, y, and z;

sensor elements for detecting at least one deflection of the plurality of masses due to the Coriolis force;

wherein a central anchoring is situated on the substrate, and the plurality of masses are arranged around the central anchoring;

wherein the subset of oscillating masses further comprises at least one mass selected from x masses and y masses, the x masses being deflectable along the z axis perpendicular to the substrate to detect yaw rates about the x axis, the y masses being also deflectable along the z axis perpendicular to the substrate to detect yaw rates about the y axis;

wherein the plurality of masses further comprises z masses, and the z masses are deflectable in the x-y plane, that is perpendicular to their respective drive direction to detect yaw rates about the z axis;

wherein the x and y masses are coupled to the central anchoring, and the z masses are coupled to at least one of the x masses and y masses; and

wherein the x and y masses are supported on the substrate such that they are linearly and tangentially drivable about the central anchoring.

2. The microgyroscope according to claim 1, wherein the x and y masses are sensor plates.

3. The microgyroscope according to claim 1, wherein the z masses are frames.

4. The microgyroscope according to claim 1, wherein the x, y, and z masses have a rectangular layout.

5. The microgyroscope according to claim 1, wherein the x masses and the y masses are mounted on the substrate via fixing anchors and drive springs.

6. The microgyroscope according to claim 5, wherein the drive springs of the x masses have controllable flexibility in the y and z directions, but are substantially inflexible in the x direction, when the microgyroscope is to detect the yaw rates about the x axis.

7. The microgyroscope according to claim 5, wherein the drive springs of the x masses have controllable flexibility in the y direction, and are substantially inflexible in the z and x directions, when the microgyroscope is to detect the yaw rates about the x axis.

8. The microgyroscope according to claim 5, wherein the drive springs of the y masses have controllable flexibility in the x direction, and are substantially inflexible in the y and z directions, when the microgyroscope is to detect no yaw rates about the y axis.

9. The microgyroscope according to claim 5, wherein the drive springs of the y masses have controllable flexibility in the x and z directions, but are substantially inflexible in the y direction, when the microgyroscope is to detect no yaw rates about the y axis.

10. The microgyroscope according to claim 1, wherein each of the x masses and the y masses is retained by an outer drive spring and an inner drive spring.

11. The microgyroscope according to claim 10, wherein each respective outer and inner drive spring is situated on the corresponding mass with controllable flexibility in the z direction when the microgyroscope is to detect the yaw rate about an axis selected from the x and y axes.

12. The microgyroscope according to claim 10, wherein each respective outer and inner drive spring is situated on the corresponding mass so as to be substantially inflexible in the z direction when the microgyroscope is to detect only the yaw rate around the z axis.

13. The microgyroscope according to claim 10, wherein the outer and inner drive springs have different lengths.

14. The microgyroscope according to claim 1, wherein the x masses and the y masses are driven by comb electrodes.

15. The microgyroscope according to claim 1, wherein the x masses are oriented and driven in the y direction, and the y masses are oriented and driven in the x direction.

16. The microgyroscope according to claim 1, wherein in each case two x masses and two y masses are arranged in alternation around the central anchoring.

17. The microgyroscope according to claim 1, wherein each of the x masses and the y masses is situated on a central spring by means of a coupling spring.

18. The microgyroscope according to claim 17, wherein the central spring is attached to the central anchoring and is designed to rotate around same in the x-y plane.

19. The microgyroscope according to claim 1, wherein the coupling spring has a spiral design, and is stiff in a tangential direction to transmit coupling forces in this direction and soft in the radial direction to avoid distortion forces on the x and y masses.

20. The microgyroscope according to claim 1, wherein one of the z masses is situated on each of the x and y masses.

21. The microgyroscope according to claim 5, wherein one of the z masses is situated on each of the x and y masses by means of connecting springs.

22. The microgyroscope according to claim 21, wherein the connecting springs are situated on a bar which is fastened substantially centrally to each of the x and y masses by a bar projection.

23. The microgyroscope according to claim 22 wherein the bar projection and the fixing anchor of each of the x and y masses are in flush alignment with one another.

24. The microgyroscope according to claim 21, wherein the connecting springs associated with the x masses have controllable flexibility in the x direction, and are substantially inflexible in the y and z directions.

25. The microgyroscope according to claim 21, wherein the connecting springs associated with the y masses have controllable flexibility in the y direction, and are substantially inflexible in the x and z directions.

26. The microgyroscope according to claim 21, wherein the microgyroscope is designed as a z gyroscope in order to detect only the yaw rates around the z axis,

the drive springs of the x masses being designed in such a way that they have controllable flexibility in the y direction, and are substantially inflexible in the z and x directions,

the drive springs of the y masses being designed in such a way that they have controllable flexibility in the x direction, and are substantially inflexible in the y and z directions,

the connecting springs associated with the x masses having controllable flexibility in the x direction and being substantially inflexible in the y and z directions, and

the connecting springs associated with the y masses having controllable flexibility in the y direction and being substantially inflexible in the x and z directions.

27. The microgyroscope according to claim 6, wherein the microgyroscope is designed as a two-dimensional gyroscope in order to detect the yaw rates about the x and y axes,

the drive springs of the x masses being designed in such a way that they have controllable flexibility in the y and z directions, but are substantially inflexible in the x direction,

the drive springs of the y masses being designed in such a way that they have controllable flexibility in the x and z directions, but are substantially inflexible in the y direction, and

the gyroscope having no z masses.

28. The microgyroscope according to claim 21, wherein the microgyroscope is designed as a three-dimensional gyroscope in order to detect the yaw rates about the x, y, and z axes,

the drive springs of the x masses being designed in such a way that they have controllable flexibility in the y and z directions, but are substantially inflexible in the x direction,

the drive springs of the y masses being designed in such a way that they have controllable flexibility in the x and z directions, but are substantially inflexible in the y direction,

the connecting springs of the z masses associated with the x masses having controllable flexibility in the x direction, and are substantially inflexible in the y and z directions, and

the connecting springs of the z masses associated with the y masses having controllable flexibility in the y direction, and are substantially inflexible in the x and z directions.