Angular rate sensor featuring mechanically decoupled oscillation modes

• US 7,520,169 B2
• Filed: 04/07/2005
• Issued: 04/21/2009
• Est. Priority Date: 04/08/2004
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Kwok; Helen C.
• Application Number:
  US11/578,024
• Publication Number:
  US 20070194857A1
• Time in Patent Office: 1,475 Days
• Field of Search: 735/040.2, 735/040.4, 735/041.2, 735/041.4, 735/041.5
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

An angular rate sensor for detecting a rotation includes 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 Fz caused by the rotational oscillation will not cause any significant radial movement of the detecting element/s or the oscillating elements. Also disclosed are different methods for operating said sensor.

Claims

1. 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 configured for performing a radial oscillation in the plane;

one or more connecting elements 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 at least one 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.

2. The angular rate sensor of claim 1, wherein the anchor structure comprises a spring assembly capable of being deflected in an oscillation plane of the oscillating element, but otherwise resisting bending.

3. The angular rate sensor of claim 1, wherein the angular rate sensor is mirror-symmetric or rotationally-symmetric.

4. The angular rate sensor of claim 1, 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.

5. The angular rate sensor of claim 1, 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.

6. The angular rate sensor of claim 1, wherein the sensor comprises a single oscillating element and the at least one detection element is disposed in recesses of the single oscillating element.

7. The angular rate sensor of claim 1, wherein the angular rate sensor includes 2, 3, 4, 6 or 8 detection elements.

8. The angular rate sensor of claim 1, wherein the angular rate sensor includes 2, 3, 4, 6 or 8 oscillating elements.

9. The angular rate sensor of claim 1, wherein the sensor comprises a single oscillating element and wherein the detection element or each of the detection elements is connected with the single oscillating element via one connecting element.

10. The angular rate sensor of claim 1, wherein the detection element or each of the detection elements is supported by two or more connecting elements.

11. The angular rate sensor of claim 1, wherein each of the one or more connecting elements is substantially rigid with respect to the rotation oscillation, such that the rotation oscillation is transmitted from the at least one oscillating element to the at least one detection element, while enabling the radial oscillation of the at least one detection element relative to the at least one oscillation element.

12. The angular rate sensor of claim 11, wherein the one or more connecting elements each comprise a spring assembly connecting one of the detection elements with one of the oscillating elements,

wherein a resonance frequency of the radial oscillation is identical with a resonance frequency of the rotation oscillation, and

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

13. 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 configured for 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.

14. The method according to claim 13, wherein the radial oscillation is measured capacitively via interdigitated structures.

15. The method of claim 13, 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.

16. The method of claim 13, 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.

17. The method of claim 13, further comprising decoupling the rotation oscillation from the radial oscillation by exciting the radial oscillation with an excitation frequency, wherein the radial oscillation having frequencies outside a resonance frequency of an excitation oscillation are strongly attenuated.

18. The method of claim 15, 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.

19. The method of claim 17, further comprising operating the angular rate sensor in vacuum to attenuate the radial oscillation with frequencies outside the resonance frequency.