Planar 3-axis inertial measurement unit

• US 20060156816A1
• Filed: 03/15/2006
• Published: 07/20/2006
• Est. Priority Date: 11/04/2003
• Status: Active Grant

• Current Assignee: Ministry of National Defense (Government of The Republic of China)
• Original Assignee: Chung-Ta Kau, Sheau-Shi Tzuoo, Shyu-Mou Chen
• Inventors: Kau, Chung-Ta, Chen, Shyu-Mou, Tzuoo, Sheau-Shi
• Granted Patent: US 7,168,317 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• 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 15/14 by making use of gyroscopes gyroscopes per se G01C19/00
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• 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 planar solid-state inertial measurement unit, manufactured mainly by a conductive material and comprising three solid-state gyroscopes installed between two parallel plates;

a first solid-state gyroscope, an angular velocity sensing axis of which is parallel to an x-axis of the plate surfaces, comprising;

a first and second sets of a proof mass and two driver bodies, a first elastic beam assembly, a first drivers assembly and a first sensors assembly;

the first and second sets of proof mass and driver bodies suspended between the two plates by the first elastic beam assembly so that the first and second sets of proof mass and driver bodies can move along a y-axis parallel to the plate surfaces, and can also move along a z-axis perpendicular to the plate surfaces;

the first drivers assembly are divided into two parts;

the first part of the first drivers being excited to drive the proof mass to vibrate in the opposite direction along the y-axis; and

the second part of the first drivers being able to sense a vibration amplitude in the opposite direction and a displacement in the same direction of the first and second sets of proof mass and driver bodies along the y-axis, and feedback it to the first part of the first drivers to control the vibration amplitude and to rebalance the specific force of the first and second proof mass along the y-axis;

the first sensors assembly being able to sense the vibration in the opposite direction and the displacement in the same direction of the first and second proof masses along the z-axis;

the first solid-state gyroscope sensing the x-axial angular velocity and the z-axial acceleration and the y-axial acceleration;

a second solid-state gyroscope, an angular velocity sensing axis of which is parallel to the y-axis of the plate surfaces, comprising;

a third and fourth sets of a proof mass and two driver bodies, a second elastic beam assembly, a second drivers assembly and a second sensors assembly;

the third and fourth sets of proof mass and driver bodies suspended between the two plates by the second elastic beam assembly so that the third and fourth sets of proof mass and driver bodies can move along the x-axis parallel to the plate surfaces, and can also move along the z-axis;

the second drivers assembly are divided into two parts;

the first part of the second drivers being excited to drive the proof mass to vibrate in the opposite direction along the x-axis; and

the second part of the second drivers being able to sense a vibration amplitude in the opposite direction and a displacement in the same direction of the third and fourth sets of proof mass and driver bodies along the x-axis, and feedback it to the first part of the second drivers to control the vibration amplitude of the third and fourth proof mass and to rebalance the specific force along the x-axis;

the second sensors assembly being able to sense the vibration in the opposite direction and the displacement in the same direction of the third and fourth proof masses along the z-axis;

the second solid-state gyroscope sensing the y-axial angular velocity and the z-axial acceleration and x-axial acceleration;

a third solid-state gyroscope, a z-axial angular velocity sensing axis of which is perpendicular to the plate surfaces, comprising;

a fifth and sixth sets of a proof mass and two driver bodies, a third elastic beam assembly, a third drivers assembly and a third sensors assembly;

the fifth and sixth sets of proof mass and driver bodies suspended between the two plates by the third elastic beam assembly so that the fifth and sixth sets of proof mass and driver bodies can move along the y-axis parallel to the plate surfaces, and can also move along the x-axis;

the third drivers assembly are divided into two parts;

the first part of the third drivers being excited to drive the proof mass to vibrate in the opposite direction along the y-axis; and

the second part of the third drivers being able to sense a vibration amplitude in the opposite direction and a displacement in the same direction of the fifth and sixth sets of proof mass and driver bodies along the y-axis, and feedback it to the first part of the third drivers to control the vibration amplitude of the fifth and sixth proof mass and to rebalance the specific force along the y-axis;

the third sensors assembly being able to sense the vibration in the opposite direction and the displacement in the same direction of the fifth and sixth proof masses along the x-axis;

the third solid-state gyroscope sensing the z-axial angular velocity and the x-axial acceleration and the y-axial acceleration;

each set of proof mass and driver bodies of each gyroscope are arranged such that the proof mass being between the two driver bodies and joined together.

2. The planar solid-state inertial measurement unit as claimed in claim 1, wherein the elastic beam assembly of each gyroscope comprises:

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

a number of first elastic beams, connecting the proof masses 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 planar solid-state inertial measurement unit as claimed in claim 2, wherein each 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.

4. The planar solid-state inertial measurement unit as claimed in claim 1, wherein each drivers assembly is constructed by:

electrodes on the surface of each plate facing to the corresponding surface of each driver body;

each surface of each driver body of the first, second and third gyroscopes respectively including a number of grooves or stripe holes perpendicular to the y-axis, x-axis, and y-axis, respectively;

the surface of each plate facing to the corresponding driver body being formed of two sets of driving electrodes, respectively including a number of stripe electrodes parallel to the grooves or stripe holes of the corresponding driver body, the two sets of driving stripe electrodes being interposed with each other and being formed of two sets of driving capacitors with the corresponding surface of the driver body.

5. The planar solid-state inertial measurement unit as claimed in claim 1, wherein

the first and second sensors assembly are respectively constructed by each surface of the first and second proof masses, and each surface of the third and fourth proof masses, and

the electrodes on the surface of each plate facing to the corresponding proof mass.

6. The planar solid-state inertial measurement unit as claimed in claim 1, wherein the third sensors assembly is constructed by

each surface of the fifth and sixth proof masses and the electrodes on the surface of each plate facing to the corresponding proof mass;

each surface of the fifth and sixth proof masses including a number of grooves or stripe holes perpendicular to the x-axis;

the surface of each plate facing to the corresponding proof mass being formed of two sets of sensing electrodes, respectively including a number of stripe electrodes parallel to the grooves or stripe holes of the proof mass, the two sets of sensing stripe electrodes being interposed with each other and being formed of two sets of sensing capacitors with the corresponding surface of the proof mass.

7. The planar solid-state inertial measurement unit as claimed in claim 1, further comprising a fourth solid-state gyroscope, a z-axial angular velocity sensing axis of which is perpendicular to the plate surfaces, the fourth solid-state gyroscope comprising:

a seventh and eighth sets of a proof mass and two driver bodies, a fourth elastic beam assembly, a fourth drivers assembly and a fourth sensors assembly;

the seventh and eighth sets of proof mass and driver bodies suspended between the two plates by the fourth elastic beam assembly so that the seventh and eighth sets of proof mass and driver bodies can move along the x-axis parallel to the plate surfaces, and can also move along the y-axis;

the fourth drivers assembly are divided into two parts;

the first part of the fourth drivers being excited to drive the proof mass to vibrate in the opposite direction along the x-axis; and

the second part of the fourth drivers being able to sense a vibration amplitude in the opposite direction and a displacement in the same direction of the seventh and eighth sets of proof mass and driver bodies along the x-axis, and feedback it to the first part of the fourth drivers to control the vibration amplitude and to rebalance the specific force of the seventh and eighth proof mass along the x-axis;

the fourth sensors assembly being able to sense the vibration in the opposite direction and the displacement in the same direction of the seventh and eighth proof masses along the y-axis;

the fourth solid-state gyroscope sensing the z-axial angular velocity and the y-axial acceleration and the x-axial acceleration.