Angular rate sensor featuring mechanically decoupled oscillation modes

• US 20070194857A1
• Filed: 04/07/2005
• Published: 08/23/2007
• Est. Priority Date: 04/08/2004
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Leonhard Olgemoeller Fricke
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Schwarzelbach, Oliver
• Granted Patent: US 7,520,169 B2
• Time in Patent Office: Days
• US Class Current: 331/23
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

The invention relates to an angular rate sensor for detecting a rotation. Said sensor comprises the following components: a substrate, at least one oscillating element that can be excited so as to oscillate rotationally or radially, an anchor structure, one or several detecting elements, one or several joining elements that connect the detecting element/s to the oscillating element, a mechanism for exciting the oscillating element, and a device for detecting a radial or rotational oscillation of the detecting element/s. Each of the detecting elements can oscillate radially on the same plane on which rotational oscillation of the oscillating element occurs, or vice versa, while the centrifugal force F_z caused by the rotational oscillation can trigger substantially no radial movement of the detecting element/s or the oscillating element/s. Also disclosed are different methods for operating said sensor.

Claims

1-19. -19. (canceled)

20. An angular rate sensor for detecting a rotation of the sensor, the sensor comprising:

a substrate;

at least one oscillating element;

an anchor structure connecting the at least one oscillating element with the substrate;

at least one detection element capable of performing a radial oscillation in a plane;

at least one connecting element connecting the at least one detection element with the at least one oscillating element;

a detection device for detecting the radial oscillation of the at least one detection element; and

an excitation device for exciting the oscillating element to perform a rotation oscillation in the plane, said rotation oscillation producing a centrifugal force imparting the at least one detection element,

wherein the centrifugal force is insufficient to initiate a radial movement of the at least one detection element.

22. The angular rate sensor of claim 20, wherein each connecting element comprises a spring assembly connecting at least one of the detection elements with at least one of the oscillating elements, wherein the spring assembly

is essentially fixed with respect to a rotation oscillation or an excitation oscillation, such that a rotation oscillation is transmitted from the at least one oscillating element to the at least one detection element and vice versa,

permits a radial oscillation of the at least one detection element with respect to the at least one oscillating element and vice versa, wherein a resonance frequency of the radial oscillation is identical with a resonance frequency of the rotation oscillation, and

attenuates a radial oscillation of the at least one detection element or of the at least one oscillating element outside the resonance frequency.

21. An angular rate sensor for detecting a rotation of the sensor, the sensor comprising:

a substrate;

at least one oscillating element performing a radial oscillation;

at least one detection element capable of performing a rotation oscillation in a plane, said rotation oscillation producing a centrifugal force acting on the at least one oscillating element;

an anchor structure connecting the at least one detection element with the substrate;

at least one connecting element which connects the at least one oscillating element with the at least one detection element;

an excitation device for exciting the at least one oscillating element to perform a radial oscillation in the plane; and

a detection device for detecting the rotation oscillation of the at least one detection element,

wherein the centrifugal force is insufficient to initiate a radial movement of the at least one detection element and does not interfere with the excitation of the at least one oscillating element.

23. The angular rate sensor of claim 21, wherein each connecting element comprises a spring assembly connecting at least one of the detection elements with at least one of the oscillating elements, wherein the spring assembly

is essentially fixed with respect to a rotation oscillation or an excitation oscillation, such that a rotation oscillation is transmitted from the at least one oscillating element to the at least one detection element and vice versa,

permits a radial oscillation of the at least one detection element with respect to the at least one oscillating element and vice versa, wherein a resonance frequency of the radial oscillation is identical with a resonance frequency of the rotation oscillation, and

attenuates a radial oscillation of the at least one detection element or of the at least one oscillating element outside the resonance frequency.

24. The angular rate sensor of claim 21, wherein the anchor structure comprises a spring assembly capable of being deflected in an oscillation plane of the oscillating element, but otherwise resisting bending.

25. The angular rate sensor of claim 21, wherein the angular rate sensor is mirror-symmetric or rotationally-symmetric.

26. The angular rate sensor of claim 21, wherein the sensor comprises a single oscillating element and the at least one detection element is farther away from the anchor structure in a radial direction than the single oscillating element.

27. The angular rate sensor of claim 21, wherein the sensor comprises a single detection element and the at least one oscillating element is farther away from the anchor structure in a radial direction than the single detection element.

28. The angular rate sensor of claim 21, wherein the sensor comprises a single oscillating element and the at least one detection element is disposed in recesses of the single oscillating element.

29. The angular rate sensor of claim 21, wherein the sensor comprises a single detection element and the at least one oscillating element is disposed in recesses of the single detection element.

30. The of claim 21, wherein the angular rate sensor includes 2, 3, 4, 6 or 8 detection elements.

31. The angular rate sensor of claim 21, wherein the angular rate sensor includes 2, 3, 4, 6 or 8 oscillating elements.

32. The angular rate sensor of claim 21, wherein the sensor comprises a single oscillating element and wherein each detection element is connected with the single oscillating element by one connecting element.

33. The angular rate sensor of claim 21, wherein the sensor comprises a single detection element and wherein each oscillating element is connected with the single detection element by one connecting element.

34. The angular rate sensor of claim 21, wherein each detection element is supported by two or more connecting elements.

35. The angular rate sensor of claim 21, wherein each oscillating element is supported by two or more connecting elements.

36. A method for detecting a rotational motion about a rotation axis with an angular rate sensor which comprises:

a substrate;

at least one oscillating element capable of performing a rotation oscillation in a plane perpendicular to the rotation axis;

an anchor structure connecting the at least one oscillating element with the substrate;

at least one detection element;

at least one connecting element connecting the at least one detection element with the at least one oscillating element;

a detection device for detecting a radial oscillation of the at least one detection element; and

an excitation device for exciting the oscillating element to perform a rotation oscillation in the plane, said rotation oscillation producing a centrifugal force imparting the at least one detection element, wherein the centrifugal force is insufficient to produce a radial motion of the at least one detection element,

wherein the at least one oscillating element is excited to perform a rotation oscillation in the plane, and

wherein the radial oscillation of the at least one detection element produced by the Coriolis force due to the rotation of the sensor about the rotation axis is detected.

38. The method according to claim 36, wherein the radial oscillation is measured capacitively by interdigitated structures.

37. A method for detecting a rotation motion about a rotation axis with an angular rate sensor which comprises:

a substrate;

at least one oscillating element performing capable of performing a radial oscillation in a plane perpendicular to the rotation axis;

at least one detection element capable of performing a rotation oscillation in a plane, said rotation oscillation producing a centrifugal force imparting the at least one oscillating element;

an anchor structure connecting the at least one detection element with the substrate;

at least one connecting element which connects the at least one oscillating element with the at least one detection element;

an excitation device for exciting the at least one oscillating element; and

a detection device for detecting the rotation oscillation of the at least one detection element,

wherein the centrifugal force is insufficient to initiate a radial movement of the at least one oscillating element,

wherein the at least one oscillating element is excited to perform the radial oscillation in the plane, and wherein the rotation oscillation of the at least one detection element caused by the Coriolis force due to the rotation of the sensor about the rotation axis is detected.

39. The method according to claim 37, wherein the rotation oscillation is measured capacitively by interdigitated structures.

40. The method of claim 37, further comprising decoupling the rotation oscillation from the radial oscillation by exciting the rotation oscillation with an excitation frequency and selecting a rotation speed so that the Coriolis force initiates a radial oscillation of the at least one detection element with the same frequency as the excitation frequency.

41. The method of claim 37, further comprising decoupling the rotation oscillation from the radial oscillation by exciting the radial oscillation with an excitation frequency and causing the Coriolis force to initiate a rotation oscillation of the at least one detection element with the same frequency as the excitation frequency.

42. The method of claim 41, wherein the radial oscillations have frequencies outside a resonance frequency of an excitation oscillation are strongly attenuated.

43. The method of claim 37, further comprising separating with an electronic filter an interfering signal with a frequency produced by the centrifugal force from a useful signal of the radial oscillation.

44. The method of claim 43, further comprising operating the angular rate sensor in vacuum to attenuate the radial oscillations with frequencies outside the resonance frequency.