Solid-state gyroscopes and planar three-axis inertial measurement unit

• US 7,197,928 B2
• Filed: 03/15/2006
• Issued: 04/03/2007
• Est. Priority Date: 11/04/2003
• Status: Active Grant

• Current Assignee: Ministry of National Defense (Government of The Republic of China)
• Original Assignee: Chung-Shan Institute of Science & Technology Armaments Bureau MND (Government of The Republic of China)
• Inventors: Kau, Chung-Ta, Chen, Shyu-Mou, Tzuoo, Sheau-Shi
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): Hanley; John C.
• Application Number:
  US11/375,029
• Publication Number:
  US 20060156815A1
• Time in Patent Office: 384 Days
• Field of Search: 735/041.2, 735/041.6, 735/041.4, 735/040.2, 735/040.4
• US Class Current: 73/504.04
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/082 for two degrees of freedom of movement of a single mass

Abstract

The present invention relates to a z-axial solid-state gyroscope. Its main configuration is manufactured with a conductive material and includes two sets of a proof mass and two driver bodies suspended between two plates by an elastic beam assembly. Both surfaces of the driver bodies and the proof masses respectively include a number of grooves respectively perpendicular to a first axis and a second axis. The surfaces of the driver bodies and the proof masses and the corresponding stripe electrodes of the plates thereof are respectively formed a driving capacitors and a sensing capacitors. The driving capacitor drives the proof masses to vibrate in the opposite direction along the first axis. If a z-axial angular velocity input, a Coriolis force makes the two masses vibrate in the opposite direction along the second axis. If a first axial acceleration input, a specific force makes the two masses move in the same direction along the first axis. If a second axial acceleration input, a specific force makes the two masses move in the same direction along the second axis. Both inertial forces make the sensing capacitances change. One z-axial solid-state gyroscopes and two in-plane axial gyroscopes can be designed on a single chip to form a complete three-axis inertial measurement unit.

Claims

1. A z-axial solid-state gyroscope, manufactured by a conductive material and comprising:

two sets of a proof mass and a corresponding two driver bodies suspended between two parallel plates by an elastic beam assembly so that they can move along a first axis and a second axis parallel to a surface of the plates;

the z-axial solid-state gyroscope sensing an angular velocity about a z-axis perpendicular to the surface of the plates and a first-axial acceleration and a second-axial acceleration;

a front and a back surfaces of each driver body forming a plurality of grooves perpendicular to the first axis, a surface of each plate facing to each driver body being formed of two sets of driving electrodes, respectively including a number of stripe electrodes perpendicular to the first axis, the two sets of driving stripe electrodes being interposed with each other to form two sets of driving capacitors with a corresponding surface of the driver body;

a front and a back surfaces of each proof mass forming a plurality of grooves perpendicular to the second axis, a surface of each plate facing to the proof mass being formed of two sets of sensing electrodes, respectively including a number of stripe electrodes parallel to the grooves of the proof mass, the two sets of sensing stripe electrodes being interposed with each other to form two sets of sensing capacitors with a corresponding surface of the proof mass;

the capacitances thereof changing with the movement of the proof masses along the second axis;

the driving capacitors of the two driver bodies corresponding to each proof mass are divided into two parts;

the first part of the driving capacitors being excited with a DC bias and an AC voltage at the mechanical resonant frequency with proper phases to drive the two proof masses to vibrate in opposite direction to each other along the first axis; and

the second part of the driving capacitors being excited with a high frequency AC voltage to sense a vibration amplitude in the opposite direction to each other and a displacement in the same direction of the two proof masses along the first axis, and feedback them to the first part of the driving capacitors to control the vibration amplitude of the two proof masses and to rebalance a specific force along the first axis;

the sensing capacitors been excited with a high frequency AC voltage to sense a vibration amplitude signal in the opposite direction and an displacement in the same direction of the two proof masses along the second axis; and

output signals of each proof mass induced by an angular velocity and an acceleration are respectively a AC signal and a DC signal, which are separated into an angular velocity signal and an acceleration signal by a signal processing means.

2. The z-axial solid-state gyroscope as claimed in claim 1, wherein the elastic beam assembly comprises:

a number of connection beams, connecting the two driver bodies corresponding to each proof mass;

a number of sensing beams, connecting each proof mass to the corresponding two driver bodies thereof and making the proof masses be able to move along the second axis;

two common connection beams, positioned at two sides of the proof masses;

a number of first elastic beams, connecting the proof masses and the driver bodies to the common connection beams; and

a number of second elastic beams, connecting the common connection beams to a central anchor fixed at the two plates.

3. The z-axial solid-state gyroscope as claimed in claim 1, wherein the elastic beam assembly comprises:

a number of sensing beams, connecting each proof mass to the corresponding two driver bodies thereof and making the proof mass be able to move along the second axis;

two common connection beams, positioned at two sides of the proof masses;

a number of first elastic beams, connecting the proof masses and the driver bodies to the common connection beams; and

a number of second elastic beams, connecting the common connection beams to a central anchor fixed at the two plates.

4. The z-axial solid-state gyroscope as claimed in claim 2, wherein the elastic beam assembly further comprises a number of third and fourth elastic beams connecting the proof masses and the driver bodies to an outer frame fixed at the two plates.

5. The z-axial solid-state gyroscope as claimed in claim 3, wherein the elastic beam assembly further comprises a number of third and fourth elastic beams connecting the proof masses and the driver bodies to an outer frame fixed at the two plates.

6. The z-axial solid-state gyroscope as claimed in claim 1, wherein each sensing capacitor is partitioned into two parts:

the first part of the sensing capacitors being excited with a high frequency AC voltage to sense an angular velocity signal perpendicular to the surface of the plates and an acceleration signal along the second axis; and

the second part of the sensing capacitors generating a feedback signal with a feedback control means to rebalance the vibration of the proof masses due to a Coriolis force and a specific force, along the second axis.