High bandwidth inertial measurement unit

• US 20090288485A1
• Filed: 05/22/2008
• Published: 11/26/2009
• Est. Priority Date: 05/22/2008
• Status: Active Grant

• Current Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Original Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Inventors: Ell, Todd A., Rutkiewicz, Robert D.
• Granted Patent: US 8,020,442 B2
• Time in Patent Office: Days
• US Class Current: 73/504.30
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01P 15/0888 for indicating angular acceleration
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 3/44 for measuring angular speed G01P3/56 takes precedence

Abstract

An inertial measurement unit is disclosed which includes a system of gyros for sensing angular rates, a system of accelerometers for sensing angular accelerations, an integrator for deriving gyro-less angular rates from the sensed angular accelerations, and a complimentary filter for blending the sensed angular rates and the gyro-less angular rates to produce a virtual angular rate output for the inertial measurement unit.

Claims

1. An inertial measurement unit comprising:

a) a system of gyros for sensing angular rates;

b) a system of accelerometers for sensing angular accelerations;

c) means for deriving gyro-less angular rates from the sensed angular accelerations; and

d) means for blending the sensed angular rates and the gyro-less angular rates to produce a virtual angular rate output for the inertial measurement unit.

2. An inertial measurement unit as recited in claim 1, wherein the system of gyros is a geometric arrangement of three gyros oriented along sense axes that are normal to three faces of a right-angled cube.

3. An inertial measurement unit as recited in claim 1, wherein the system of accelerometers is a geometric arrangement of six accelerometers oriented along sense axes that are diagonal across the faces of a right-angled cube.

4. An inertial measurement unit as recited in claim 1, wherein the system of accelerometers is adapted and configured to sense linear acceleration and angular acceleration.

5. An inertial measurement unit as recited in claim 2, further comprising means for generating a total angular rate from the sensed angular rates of the three gyros.

6. An inertial measurement unit as recited in claim 5, wherein the means for generating a total angular rate from the sensed angular rates of the three gyros includes a configuration matrix.

7. An inertial measurement unit as recited in claim 3, further comprising means for generating a total angular acceleration from the sensed angular accelerations of the six accelerometers.

8. An inertial measurement unit as recited in claim 7, wherein the means for generating a total angular acceleration from the sensed angular accelerations of the six accelerometers includes a configuration matrix.

9. An inertial measurement unit as recited in claim 7, wherein the means for deriving gyro-less angular rates from sensed angular accelerations includes means for integrating the total angular acceleration.

10. An inertial measurement unit as recited in claim 1, further comprising a high-pass filter for removing low frequency noise from the gyro-less angular rates.

11. An inertial measurement unit as recited in claim 1, further comprising a low-pass filter for removing high frequency noise from the total angular rate.

12. A method of inertial measurement comprising the steps of:

a) sensing angular rates;

b) sensing angular accelerations;

c) deriving gyro-less angular rates from the sensed angular accelerations; and

d) blending the sensed angular rates and the gyro-less angular rates to produce a total virtual angular rate output.

13. A method of inertial measurement according to claim 12, wherein the angular rates are sensed by a system of three gyros oriented along sense axes that are normal to three faces of a right-angled cube.

14. A method of inertial measurement according to claim 12, wherein the angular accelerations are sensed by a system of six accelerometers oriented along sense axes that are diagonal across the faces of a right-angled cube.

15. A method of inertial measurement according to claim 12, further comprising the step of sensing linear accelerations.

16. A method of inertial measurement according to claim 13, further comprising the step of generating a total angular rate from the angular rates sensed by each of the three gyros.

17. A method of inertial measurement according to claim 14, further comprising the step of generating a total angular acceleration from the angular accelerations sensed by each of the six accelerometers.

18. A method of inertial measurement according to claim 14, wherein the step of deriving gyro-less angular rates from the sensed angular acceleration includes the step of integrating the total angular acceleration.

19. A method of inertial measurement according to claim 12, further comprising the step of filtering the gyro-less angular rates to remove low frequency noise.

20. A method of inertial measurement according to claim 12, further comprising the step of filtering the total angular rates to remove high frequency noise.