Rotational rate gyroscope with decoupled orthogonal primary and secondary oscillations

• US 6,561,029 B2
• Filed: 11/06/2001
• Issued: 05/13/2003
• Est. Priority Date: 10/07/1996
• Status: Expired due to Term

• Current Assignee: Hahn-Schickard-Gesellschaft für angewandte Forschung e.V.
• Original Assignee: Hahn-Schickard-Gesellschaft für angewandte Forschung e.V.
• Inventors: Lang, Walter, Folkmer, Bernd, Sobe, Udo, Geiger, Wolfram
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US10/039,926
• Publication Number:
  US 20020088279A1
• Time in Patent Office: 553 Days
• Field of Search: 735/041.2, 735/040.2, 735/040.4
• US Class Current: 73/504.14
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

A rotational rate gyroscope for detecting rotation thereof comprises a base member, a primary oscillator supported by its primary oscillator suspension so as to be movable with respect to the base member, and a secondary oscillator supported by a secondary oscillator suspension, separate from primary oscillator suspension, so as to be movable with respect to the primary oscillator. The secondary oscillator suspension is designed such that movement that can be applied to the primary oscillator can be transferred to the secondary oscillator, whereas the movement of the secondary oscillator effected by the Coriolis force substantially is not transferred back to the primary oscillator. In addition thereto, the major surfaces of the primary oscillator and of the secondary oscillator extend substantially in the same plane, with the movement of the primary oscillator and/or of the secondary oscillator also taking place in this plane.

Claims

1. A rotational rate gyroscope for detecting rotation thereof, about a first axis and a third axis, comprising the following features:

a base member;

a primary oscillator;

exciting means for exciting the primary oscillator with respect to the base member to perform a primary movement which is directed along a second axis, the first axis, the second axis and the third axis being substantially normal to each other;

a secondary oscillator adapted to be caused, by a Coriolis force, to perform a secondary movement which is directed along the third axis in case of a rotation about the first axis, and which is directed along the first axis in case of a rotation about the third axis, with major surfaces of the primary oscillator and the secondary oscillator extending substantially in a plane, defined by the first axis and the second axis, and the movement of the primary oscillator taking place in this plane;

a primary oscillator suspension for holding the primary oscillator so as to be movable with respect to the base member along the second axis, while a movement of the primary oscillator with respect to the base member along the first axis and the third axis is substantially prevented;

a secondary oscillator suspension being separate from the primary oscillator suspension for connecting the primary oscillator to the secondary oscillator,

the secondary oscillator suspension being formed such

that it transfers the primary movement to the secondary oscillator substantially in rigid manner;

that it allows a movement of the secondary oscillator with respect to the primary oscillator in the directions of the third axis and the first axis; and

that it substantially prevents a transfer of the secondary movement back to the primary oscillator;

first detection means for detecting a movement of the secondary oscillator along the first axis, the first detection means having a secondary oscillator electrode group attached to the secondary oscillator and having a fixed sensing electrode group attached to the base member,

the secondary electrode group and the fixed sensing electrode group being in a comb-like interengagement; and

second detection means for detecting a movement of the secondary oscillator along the third axis, the second detection means having the secondary oscillator as a movable electrode and a fixed sensing electrode, which is attached to the base member.

2. The rotational rate gyroscope according to claim 1, wherein the primary oscillator suspension comprises a plurality of spring beams extending in the direction of the first axis, being deflectable in the direction of the second axis, and being connected to the base member via anchoring means.

3. The rotational rate gyroscope according to claim 2,

wherein the spring beams have a rectangular cross section having a narrow side and a long side, the narrow side extending along the second axis, and the long side extending along the third axis.

4. The rotational rate gyroscope according to claim 1,

wherein the exciting means comprises at least one electrode group which is in engagement with a fixed electrode group so as to capacitively excite the primary oscillator parallel to the second axis in order to obtain the primary movement.

5. The rotational rate gyroscope according to claim 1,

wherein the primary oscillator comprises a recess in which the secondary oscillator is positioned by means of the secondary oscillator suspension, and in which also the first and the second detection means are arranged.

6. The rotational rate gyroscope according to claim 1,

wherein the secondary oscillator suspension comprises a plurality of spring beams disposed parallel to the second axis and connecting the primary oscillator to the secondary oscillator, the spring beams furthermore being of substantially square cross-section so as to permit a deflection both in the z direction and in the y direction.

7. The rotational rate gyroscope according to claim 1,

wherein the second detection means further comprises a cover electrode being arranged with respect to the fixed sensing electrode such that the secondary oscillator is disposed between the cover electrode and the fixed sensing electrode in order to allow differentially measuring the secondary movement along the third axis.