Apparatus for Three-Axis IMU Calibration with a Single-Axis Rate Table

• US 20170199054A1
• Filed: 03/01/2016
• Published: 07/13/2017
• Est. Priority Date: 03/03/2015
• Status: Active Grant

• Current Assignee: West Virginia University
• Original Assignee: West Virginia University
• Inventors: Christian, John A., Bittner, Drew E.
• Granted Patent: US 9,970,781 B2
• Time in Patent Office: Days
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

Various methods and apparatuses are provided for calibrating a three-axis IMU sensor package using a single-axis rate table. In one embodiment, a method includes adjusting an x-axis position of a sensor by rotating an inner assembly along the circumference of the inner surface of the circular frame, adjusting a y-axis position of the sensor by rotating a portion of the inner assembly, spinning the single-axis rate table to generate z-axis rotation of the apparatus which results in simultaneous stimulation of all three axes of the sensor assembly, and obtaining measurements from the sensor corresponding to the x-axis position, the y-axis position, and the z-axis rotation of the apparatus.

Claims

1. A mounting apparatus for calibrating a sensor package using a single-axis rate table, the mounting apparatus comprising:

a circular frame;

an inner assembly slidably coupled to the circular frame and extending along a diameter of the circular frame, the inner assembly being configured to secure the sensor package, and rotation of the inner assembly about an inner circumference of the circular frame corresponding to an x-axis position of the sensor package; and

a bracket mount attached to a portion of the circular frame, the bracket mount being configured for mounting the mounting apparatus onto the single-axis rate table.

2. The mounting apparatus of claim 1, wherein the circular frame comprises a plurality of x-rotation holes positioned around the inner circumference of the circular frame.

3. The mounting apparatus of claim 2, wherein the plurality of x-rotation holes are uniformly spaced along the inner circumference of the circular frame.

4. The mounting apparatus of claim 2, wherein a position of the inner assembly along the circular frame is based at least in part on one or more of the plurality of x-rotation holes, the inner assembly being secured to the circular frame at the position via one or more x-mounting pins inserted into one or more a-mounting holes on the inner assembly aligned with the one or more of the plurality of x-rotation holes, the one or more x-mounting pins extending into the one or more of the plurality of x-rotation holes.

5. The mounting apparatus of claim 1, wherein the rotation of the mounting apparatus about a z-axis coincides with rotation of the single-axis rate table.

6. The mounting apparatus of claim 1, wherein the inner assembly comprises a first slide member and a second slide member, the first slide member being slidably coupled to the circular frame at a first location and the second slide member being slidably coupled to the circular frame at a second location, the first location being opposite of the second location.

7. The mounting apparatus of claim 6, wherein the inner assembly further comprises a sensor mount assembly coupled to a y-axis assembly, the y-axis assembly being rotationally coupled to the second slide member.

8. The mounting apparatus of claim 7, wherein a y-axis rotation of the sensor package corresponds to a rotation of the y-axis assembly about the second slide member.

9. The mounting apparatus of claim 7, wherein the second slide member comprises a plurality of y-rotation holes spaced in a circular configuration, wherein a y-axis orientation of the sensor mount is based at least in part on an alignment of a y-mounting hole on the y-axis assembly with a respective y-rotation hole.

10. The mounting apparatus of claim 1, wherein the sensor comprises a three-axis Inertial Measurement Unit (IMU) sensor package.

11. A method, comprising:

attaching a mounting apparatus comprising a sensor to a single-axis rate table;

adjusting an x-axis position of the sensor by rotating an inner assembly along a circumference of a circular frame of the mounting apparatus, the sensor being mounted to the inner assembly;

adjusting a y-axis position of the sensor by rotating a portion of the inner assembly, the sensor being coupled to the portion of the inner assembly; and

spinning the single-axis rate table to generate z-axis rotation of the mounting apparatus and stimulating a combination of the x-axis, y-axis, and z-axis of the sensor based at least in part on the x-axis position, the y-axis position, and the z-axis rotation.

12. The method of claim 11, further comprising obtaining one or more measurements from the sensor corresponding to the x-axis position, the y-axis position, and the z-axis rotation of the mounting apparatus.

13. The method of claim 12, wherein the one or more measurements comprise at least one of an x-axis accelerometer measurement, a y-axis accelerometer measurement, a z-axis accelerometer measurement, an x-axis gyroscope measurement, a y-axis gyroscope measurement, a z-axis gyroscope measurement, or a sensor package temperature measurement.

14. The method of claim 11, wherein the inner assembly is slidably coupled to an inner surface of the circular frame.

15. The method of claim 11, further comprising aligning one or more a-mounting holes on the inner assembly with one or more x-rotation holes on the circular frame, the one or more x-rotation holes being associated with the x-axis position.

16. The method of claim 15, further comprising securing the x-axis position by inserting one or more locking pins into the one or more x-mounting holes aligned with the one or more x-rotation holes on the inner assembly.

17. The method of claim 11, further comprising aligning a y-mounting hole on a y-axis assembly of the inner assembly with a specific y-rotation hole on a slide member of the inner assembly, the specific y-rotation hole being associated with the y-axis position.

18. The method of claim 17, further comprising securing the y-axis position by inserting a locking pin into the y-mounting hole and the specific y-rotation hole when the y-mounting hole is aligned with the specific y-rotation hole.

19. The method of claim 11, wherein the sensor comprises an Inertial Measurement Unit (IMU) sensor package.

20. An apparatus for calibrating a three axis Inertial Measurement Unit (IMU) sensor package on a single-axis rate table, the apparatus comprising:

means for rotating the IMU sensor package along an x-axis;

means for rotating the IMU sensor package along a y-axis; and

means for mounting the IMU sensor package to the single-axis rate table, the rotation of the IMU sensor package coinciding with rotation of the single-axis rate table and resulting an a controlled and simultaneous stimulation of all three axes of the IMU sensor package.