Inertial measurement unit and method of constructing the same using two orthogonal surfaces

• US 8,056,412 B2
• Filed: 09/10/2008
• Issued: 11/15/2011
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Original Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Inventors: Stuelke, Robert W., Ell, Todd A., Rutkiewicz, Robert D.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US12/208,106
• Publication Number:
  US 20100058860A1
• Time in Patent Office: 1,161 Days
• Field of Search: 734/93, 735/041.2, 735/10, 735/140.1
• US Class Current: 73/493
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems

Abstract

A method of mounting in-plane sensors of an inertial measurement unit. The method includes the steps of: providing a structure having first and second planar surfaces oriented orthogonally to one another, positioning a plurality of sensors on the first planar surface such that each of the sensors has a sense axis extending parallel to the first planar surface, positioning at least one other sensor on the second planar surface such that the at lease one other sensor has a sense axis extending parallel to the second planar surface, and orienting the sensors on the first and second surfaces so that the angles formed between any two sense axes are equal.

Claims

1. A method of mounting in-plane sensors, comprising the steps of:

providing a structure having first and second planar surfaces oriented orthogonally to one another;

positioning at least two sensors on the first planar surface such that each of the sensors has a sense axis extending parallel to the first planar surface;

positioning at least two other sensors on the second planar surface such that the at least two other sensors each has a sense axis extending parallel to the second planar surface; and

orienting the sensors on the first and second surfaces so that the angles formed between any two sense axes are equal.

2. The method of claim 1, wherein the step of orienting the sensors includes orienting the sensors such that any two sense axes are oriented at an outer angle of 109.47 degrees relative to one another.

3. The method of claim 1, further comprising the step of providing a third planar surface on the structure, oriented at an angle of 45 degrees with respect to both the first planar surface and the second planar surface.

4. The method of claim 3, further comprising the step of positioning a first redundant sensor on the third planar surface such that a sense axis of the first redundant sensor is parallel to the third planar surface.

5. The method of claim 4, further comprising the step of mounting a second redundant sensor on any one of the first, second, and third planar surfaces such that a sense axis of the second redundant sensor is parallel to both the second planar surface and the first planar surface, and is perpendicular to the sense axis of the first redundant sensor.

6. An inertial measurement unit, comprising:

a structure having a first planar surface and a second planar surface oriented orthogonally to one another;

at least two primary sensors mounted on the first planar surface, wherein each of the primary sensors has a sense axis that extends parallel to the first planar surface; and

at least two primary sensors mounted on the second planar surface, wherein the each primary sensor mounted on the second planar surface has a sense axis that is parallel to the second planar surface, and wherein the outer angle formed between any two sense axes is equal to approximately 109.47 degrees.

7. The inertial measurement unit of claim 6, further comprising a redundant sensor mounted on the first planar surface, the redundant sensor having a sense axis with an identical orientation to one of the primary sensors mounted on the first planar surface.

8. The inertial measurement unit of claim 6, wherein the structure is a triangular prism including a third planar surface connecting the first planar surface and the second planar surface, wherein the third planar surface is oriented at an angle of 45 degrees with respect to both the first and second planar surface.

9. The inertial measurement unit of claim 6, wherein the primary sensors are accelerometers.

10. The inertial measurement unit of claim 6, wherein the primary sensors are gyroscopic rotational rate sensors.

11. A method for providing a tetrahedral angle configuration for a three-axis inertial measurement unit on two mounting surfaces, the method comprising:

providing a structure having a first planar surface and a second planar surface oriented orthogonally to one another, and a linear junction formed at the intersection of the first and second planar surfaces;

mounting a first sensor on the first planar surface such that a sense axis of the first sensor is parallel to the first planar surface and oriented at an inner angle of approximately 54.74 degrees from the linear junction;

mounting a second sensor on the first planar surface such that a sense axis of the second sensor is parallel to the first planar surface and oriented at an inner angle of approximately 54.74 degrees from the linear junction;

mounting a third sensor on the second planar surface such that a sense axis of the third sensor is parallel to the second planar surface and is oriented at an inner angle of approximately 54.74 degrees from the linear junction; and

mounting a fourth sensor on the second planar surface such that a sense axis of the fourth sensor is parallel to the second planar surface and is oriented at an inner angle of approximately 54.74 degrees from the linear junction.

12. The method of claim 11, further comprising mounting an additional redundant sensor on any one of the first planar surface and the second planar surface.