High bandwidth inertial measurement unit

• US 8,020,442 B2
• Filed: 05/22/2008
• Issued: 09/20/2011
• Est. Priority Date: 05/22/2008
• Status: Expired due to Fees

• Current Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Ell, Todd A., Rutkiewicz, Robert D.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US12/154,400
• Publication Number:
  US 20090288485A1
• Time in Patent Office: 1,216 Days
• Field of Search: 735/10, 735/03, 735/040.2, 735/140.2, 701/220
• US Class Current: 73/510
• 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 low bandwidth gyros for sensing angular rates;

b) a system of high bandwidth 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 derived gyro-less angular rates to produce a virtual angular rate output for the inertial measurement unit, wherein the virtual angular rate output possesses the higher bandwidth associated with the accelerometers, such that an overall bandwidth of the inertial measurement unit is aligned with the bandwidth of the accelerometers.

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 2, further comprising means for generating a total angular rate from the sensed angular rates of the three gyros.

4. An inertial measurement unit as recited in claim 3, wherein the means for generating a total angular rate from the sensed angular rates of the three gyros includes a configuration matrix.

5. An inertial measurement unit as recited in claim 3, further comprising a low-pass filter for removing high frequency noise from the total angular rate generated from the sensed angular rates of the three gyros.

6. 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.

7. An inertial measurement unit as recited in claim 6, 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, wherein the system of accelerometers is adapted and configured to sense linear acceleration and angular acceleration.

11. 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.

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

a) sensing angular rates using a system of low bandwidth gyros;

b) sensing angular accelerations using a system of high bandwidth accelerometers;

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

d) blending the sensed angular rates and the derived gyro-less angular rates to produce a total virtual angular rate output possessing the higher bandwidth associated with the accelerometers.

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 13, further comprising the step of generating a total angular rate from the angular rates sensed by each of the three gyros.

15. A method of inertial measurement according to claim 14, further comprising the step of filtering the total angular rate generated from the angular rates sensed by each of the three gyros to remove high frequency noise.

16. 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.

17. A method of inertial measurement according to claim 16, 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 17, 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 sensing linear accelerations.

20. 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.