Microelectromechanical gyroscope with compensation of quadrature error drift

• US 9,404,747 B2
• Filed: 10/30/2013
• Issued: 08/02/2016
• Est. Priority Date: 10/30/2013
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Valzasina, Carlo, Falorni, Luca Giuseppe
• Primary Examiner(s): Kwok, Helen
• Application Number:
  US14/067,051
• Publication Number:
  US 20150114112A1
• Time in Patent Office: 1,007 Days
• Field of Search: 735/041.2, 735/041.4, 735/040.2, 735/040.4
• US Class Current: 1/1
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• 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
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

A microelectromechanical gyroscope, includes: a supporting body; a first movable mass and a second movable mass, which are oscillatable according to a first driving axis and tiltable about respective a first and second sensing axes and are symmetrically arranged with respect to a center of symmetry; first sensing electrodes and a second sensing electrodes associated with the first and second movable masses and arranged on the supporting body symmetrically with respect to the first and second sensing axis, the first and second movable masses being capacitively coupled to the respective first sensing electrode and to the respective second sensing electrode, a bridge element elastically coupled to respective inner ends of the first movable mass and of the second movable mass and coupled to the supporting body so as to be tiltable about an axis transverse to the first driving axis.

Claims

1. A microelectromechanical gyroscope, comprising:

a supporting body;

a first movable mass configured to oscillate with respect to the supporting body along a first driving axis and configured to rotate about a first sensing axis;

a second movable mass configured to oscillate with respect to the supporting body along the first driving axis and configured to rotate around a second sensing axis;

a first plurality of driving electrodes positioned within the first moveable mass;

a second plurality of driving electrodes positioned within the second moveable mass;

a first sensing electrode and a second sensing electrode associated with the first movable mass and arranged on the supporting body symmetrically with respect to the first sensing axis, the first movable mass being capacitively coupled to the first sensing electrode and to the second sensing electrode, the first and second sensing electrodes being separated by the first plurality of driving electrodes; and

a third sensing electrode and a fourth sensing electrode associated with the second movable mass and arranged on the supporting body symmetrically with respect to the second sensing axis, the second movable mass being capacitively coupled to the third sensing electrode and to the fourth sensing electrode, the third and fourth sensing electrodes being separated by the second plurality of driving electrodes.

2. A gyroscope as claimed in claim 1, further comprising a bridge element elastically coupled to respective inner ends of the first movable mass and of the second movable mass and coupled to the supporting body, the bridge element configured to rotate about an axis transverse to the first driving axis.

3. A gyroscope as claimed in claim 1 wherein the first sensing electrode and the second sensing electrode associated with the first movable mass are arranged within a perimeter of the first movable mass and the third sensing electrode and the fourth sensing electrode associated with the second movable mass are arranged within a perimeter of the second movable mass.

4. A gyroscope as claimed in claim 1 wherein the first driving axis, the first sensing axis, and the second sensing axis are parallel to a surface of the supporting body.

5. A gyroscope as claimed in claim 4 wherein the first sensing axis and the second sensing axis are parallel to each other and perpendicular to the first driving axis.

6. A gyroscope as claimed in claim 1 wherein the first movable mass and the second movable mass are symmetrically arranged with respect to a center of symmetry.

7. A gyroscope as claimed in claim 2 wherein the bridge element is configured to bind the first movable mass and the second movable mass to rotate both clockwise or both counter-clockwise.

8. A gyroscope as claimed in claim 1, further comprising:

a third movable mass configured to oscillate with respect to the supporting body along a second driving axis and configured to rotate about a third sensing axis;

a fourth movable mass configured to oscillate with respect to the supporting body along the second driving axis and configured to rotate about a fourth sensing axis;

a fifth sensing electrode and a sixth sensing electrode associated with the third movable mass and arranged on the supporting body symmetrically with respect to the third sensing axis, the third movable mass being capacitively coupled to the fifth sensing electrode and the sixth sensing electrode; and

a seventh sensing electrode and an eighth sensing electrode associated with the fourth movable mass and arranged on the supporting body symmetrically with respect to the fourth sensing axis, the fourth movable mass being capacitively coupled to the seventh sensing electrode and the eighth sensing electrode.

9. A gyroscope as claimed in claim 8 wherein the fifth, sixth, seventh, and eighth sensing electrodes are arranged between the supporting body and the respective one of the third movable mass and fourth movable mass.

10. A gyroscope as claimed in claim 8 wherein the fifth and sixth sensing electrodes associated with the third movable mass are arranged within a perimeter of the third movable mass and the seventh and eighth sensing electrodes associated with the fourth movable mass are arranged within a perimeter of the fourth movable mass.

11. A gyroscope as claimed in claim 8 wherein the second driving axis is perpendicular to the first driving axis and the third and fourth sensing axes are parallel to each other and perpendicular to first and second sensing axes.

12. A gyroscope as claimed in claim 8, further comprising a bridge element elastically coupled to respective inner ends of the first movable mass and of the second movable mass and coupled to the supporting body, the bridge element being elastically coupled to respective inner ends of the third movable mass and of the fourth movable mass and is coupled to the supporting body, the bridge element configured to rotate about an axis transverse to the first driving axis and about an axis transverse to the second driving axis.

13. A gyroscope as claimed in claim 12 wherein the bridge element is configured to bind the third movable mass and the fourth movable mass to rotate both clockwise or both counter-clockwise.

14. A gyroscope according to claim 1, further comprising a driving structure, configured to provide electrostatic driving forces between the supporting body and at least one of the first movable mass and second movable mass in response to driving voltages, thereby causing the first movable mass and second movable mass to move symmetrically in opposite directions along the first driving axis.

15. A gyroscope according to claim 1 wherein the first sensing electrodes and the second sensing electrodes are arranged between the supporting body and the respective one of the first movable mass and second movable mass.

22. The gyroscope of claim 1 wherein the first and second movable masses have a trapezoidal shape.

23. The gyroscope of claim 1 wherein the first and second sensing electrodes have a trapezoidal shape.

24. The gyroscope of claim 1 wherein the first and second sensing electrodes and the third and fourth sensing electrodes have a trapezoidal shape.

16. An electronic system, comprising:

a control unit;

a microelectromechanical gyroscope coupled to the control unit, the gyroscope including;

a supporting body;

a first movable mass configured to oscillate with respect to the supporting body along a first driving axis and configured to rotate about a first sensing axis;

a second movable mass configured to oscillate with respect to the supporting body along the first driving axis and configured to rotate around a second sensing axis;

a first sensing electrode and a second sensing electrode associated with the first movable mass and arranged on the supporting body symmetrically with respect to the first sensing axis, the first movable mass being capacitively coupled to the first sensing electrode and to the second sensing electrode;

a third sensing electrode and a fourth sensing electrode associated with the second movable mass and arranged on the supporting body symmetrically with respect to the second sensing axis, the second movable mass being capacitively coupled to the third sensing electrode and to the fourth sensing electrode;

a first support positioned between the first movable mass and the supporting body, the first support anchored to the supporting body between the first sensing electrode and the second sensing electrode; and

a second support positioned between the second movable mass and the supporting body, the second support anchored to the supporting body between the third sensing electrode and the fourth sensing electrode.

17. The system of claim 16 wherein the first sensing electrodes and the second sensing electrodes are arranged between the supporting body and the respective one of the first movable mass and second movable mass.

18. A device, comprising:

a substrate;

a first mass suspended above the substrate;

a second mass suspended above the substrate and elastically coupled to the first mass;

a first support coupled between the substrate and the first mass, the first mass being configured to rotate about a first sensing axis that corresponds to a location where the first support is coupled to the first mass;

a second support coupled between the substrate and the second mass, the second mass being configured to rotate about a second sensing axis that corresponds to a location where the second support is coupled to the second mass;

a first pair of electrodes positioned on the substrate and configured to interact with the first mass, the first pair of electrode being separated from each other by the first support; and

a second pair of electrodes positioned on the substrate and configured to interact with the second mass, the second pair of electrode being separated from each other by the second support.

19. The device of claim 18, further comprising:

a connection member elastically coupled between the first mass and the second mass; and

a third support coupled between the connection member and the substrate.

20. The device of claim 19 wherein the third support is configured to rotate about the third support along a third axis that is parallel to the first and the second sensing axis.

21. The device of claim 18, further comprising:

a third mass suspended above the substrate;

a fourth mass suspended above the substrate and elastically coupled to the third mass; and

a central connection member, the first and second masses being symmetrically arranged on opposite sides of the central connection member, and the third and fourth masses being symmetrically arranged on opposite sides of the central connection member.