Method and apparatus for a rotation angle sensor

• US 6,204,499 B1
• Filed: 06/05/1998
• Issued: 03/20/2001
• Est. Priority Date: 06/05/1997
• Status: Expired due to Fees

• Current Assignee: Zodiac Automotive US, Inc.
• Original Assignee: BAE Systems Simula, Inc. (Safariland LLC)
• Inventors: Schaefer, Philip
• Primary Examiner(s): Lee, John R.
• Application Number:
  US09/092,553
• Time in Patent Office: 1,019 Days
• Field of Search: 250/216, 250/227.11, 250/227.14, 250/231.1, 250/231.13, 250/237 R, 250/237 G, 341/14, 73/862.23, 73/862.26
• US Class Current: 250/231.1
• CPC Class Codes: G01D 5/30 the beams of light being detected by photocells
• CPC Class Codes: G01P 15/006 by making use of fluid seismic masses
• CPC Class Codes: G01P 15/0888 for indicating angular acceleration
• CPC Class Codes: G01P 15/093 by photoelectric pick-up

Abstract

A rotation angle sensor has a fluid-filled container which houses a vane immersed in the fluid. The vane which rotates freely with respect to the container. The container is fixedly attached to a body for which rotation angle measurement is desired. When the body, and therefore container rotates, the fluid, and therefore vane tend to remain fixed with respect tot he rotation. The angle of rotation can therefore be measured by determining the amount the container has rotated with respect to the vane.

Claims

1. A rotation angle sensor, comprising:

(a) a fluid-filled container, having a top and a bottom; and

(b) a vane connected to the top and bottom of said fluid-filled container via a shaft, so as to remain substantially fixed with respect to an axis of rotation and allowing the container to rotate freely about the vane, such that the vane remains substantially fixed as the container rotates about the vane.

2. The rotation angle sensor of claim 1, wherein said vane is imbalanced.

3. The rotation angle sensor of claim 1, wherein said vane diffusely scatters light by reflection, further comprising:

a light source to illuminate said vane;

a first light detector to detect light reflecting from said vane as a first light intensity measurement;

a second light detector to detect light reflecting from said vane as a second light intensity measurement; and

a computational device to determine a rotation angle using said first and second light intensity measurements.

4. The rotation angle sensor of claim 1, wherein said vane diffusely scatters light by reflection, further comprising:

a first light source to illuminate said vane;

a second light source to illuminate said vane;

a light detector to detect light reflecting from said vane as a light intensity measurement, wherein light reflecting from said vane due to illumination by said first light source is a first light intensity measurement and light reflecting from said vane due to said second light source is a second light intensity measurement;

means for alternating illumination of said vane by said first and second light sources; and

a computational device to determine a rotation angle using said first and second light intensity measurements.

5. The rotation angle sensor of claim 1, wherein said vane diffusely scatters light by reflection, further comprising:

a light source to illuminate said vane;

a photodiode to detect light reflecting from said vane as a light intensity measurement;

a computational device to determine a rotation angle using said light intensity measurements.

6. The rotation angle sensor of claim 1, wherein said vane has a hole, further comprising:

a light source to transmit light through the hole;

a light detector to detect light transmitted through said hole by said LED as a light intensity measurement;

a computational device to determine a rotation angle using said light intensity measurements.

7. The rotation angle sensor of claim 1, further comprising:

a cam fixably attached to said vane;

one or more pairs of electrodes, each pair have a first electrode one side of said cam, and a second electrode on another side of said cam;

a current source connected across each pair of electrodes; and

a computational device to determine a rotation angle using an impedance measureable across each eletrode pair.

8. The rotation angle sensor of claim 1, further comprising:

a fiber optic cable fixably attached to said vane to form a loop;

an optical processor having a light source to send a pulse through one oend of said fiber optic cable and an optical detector to detect light intensity returning at the other end of said cable;

and a computation device to determine rotation angle based on said light intensity.

9. The rotation angle sensor of claim 1, further comprising a transparent ring attached to said vane.

10. The rotation angle sensor of claim 1, wherein said vane comprises a plurality of panels.

11. The rotation angle sensor of claim 10, further comprising ring attached to said vane.

12. The rotation angle sensor of claim 11, wherein said ring has a relfective coating of varying width to indicate location on said ring.

13. The rotation angle sensor of claim 12, wherein said ring has a digital code to indicate location on said ring encoded thereon.

14. An angular velocity sensor, comprising:

a sealed fluid-filled container; and

a cantilever having one end fixably attached to an inside surface of said container, so that a bend of the cantilever can be measured when the container is subjected to an angular velocity.

15. The angular velocity detector of claim 14, further comprising:

a loop of fiber optic cable attached to said cantilever.

16. A method for determining angle of rotation, comprising the steps of:

(a) connecting a vane in a fluid filled container having a top and a bottom via a shaft so that the vane remains substantially fixed with respect to an axis of rotation;

(b) allowing the container to rotate freely about the vane, such that the vane remains substantially fixed as the container rotates about the vane; and

(c) determining an angle of rotation of the cylinder from an initial point.

17. The method of claim 16, further comprising the steps of

(b) alternating illuminating of said vain by between two light sources;

(c) detecting light reflected by the vane in response to illumination by each light source; and

(d) determining the angle of rotation based on said reflected light.

18. The method of claim 16, further comprising the steps of:

(b) illuminating said vane by a light source;

(c) detecting light reflected from said vane; and

(d) determining the angle of rotation based on said reflected light.

19. The method of claim 16, further comprising the step of:

(b) attaching a cam to said vane.

20. The method of claim 16, further comprising the step of:

(b) attaching a loop of fiber optic cable to said vane.

21. A method for determining angular velocity, comprising the steps of:

(a) mounting a cantilever in a fluid-filled container;

(b) measuring the amount of bend of said cantilever; and

(c) determining the angular velocity in accordance with the amount of bend of said cantilever.

22. The method of claim 21, further comprising the steps of:

(d) attaching a fiber optic loop to said cantilever;

(e) sending a light through said loop;

(f) receiving said light as a received light; and

(g) determining angular velocity in accordance with said received lights.

23. A rotation sensor for mounting in a vehicle to sense rotation of a vehicle about an axis, comprising:

a container filled with a fluid that is sealed to prevent flow of the fluid through the container;

a vane connected to a top and a bottom of the container so that the container can rotate freely about the vane via a shaft, the shaft defining an axis of rotation about which the rotation is sensed.

24. The rotation sensor recited in claim 23, wherein the vane is imbalanced.

25. The rotation sensor recited in claim 23, wherein the vane diffusely scatters light by reflection, further comprising:

a light source to illuminate said vane;

a first light detector to detect light reflecting from the vane as a first light intensity measurement;

a second light detector to detect light reflecting from the vane as a second light intensity measurement; and

a computational device to determine an angle of rotation using the first and second light intensity measurements.

26. The rotation sensor recited in claim 23, wherein the vane diffusely scatters light by reflection, further comprising:

a first light source to illuminate said vane;

a second light source to illuminate the vane;

a light detector to detect light reflecting from the vane as a light intensity measurement, wherein light reflecting from the vane due to illumination by the first light source is a first intensity measurement and light reflecting from the vane due to the second light source is a second intensity measurement;

means for alternating illumination of the vane by the first and second light sources; and

a computational device to determine a rotation;

angle using the first and second light intensity measurements.

27. The rotation sensor recited in claim 23, wherein the vane diffusely scatters light by reflections further comprising:

a light source to illuminate the vane;

a photodiode to detect light reflecting from the vane as a light intensity measurement; and

a computational device to determine a rotation angle using the light intensity measurement.

28. The rotation sensor recited in claim 23, wherein the vane has a hole, further comprising:

a light source to transmit light through the hole;

a light detector to detect light transmitted through the hole by the light source as a light intensity measurement; and

a computational device to determine a rotation angle using the light intensity measurement.

29. The rotation sensor recited in claim 23, further comprising:

a cam fixably attached to the vane;

one or more pairs of electrodes, each pair having a first electrode on one side of the cam, and a second electrode on another side of the cam;

a current source connected across each pair of electrodes; and

a computational device to determine a rotation angle using an impedance measurable across each electrode pair.

30. The rotation sensor recited in claim 23, further comprising:

a fiber optic cable fixably attached to the vane to form a loop;

an optical processor having a light source to send a pulse through one end o the fiber optic cable and an optical detector to detect light intensity returning at the other end of the cable; and

a computational device to determine rotation angle based on the light intensity.

31. A method for sensing rotation of a vehicle about an axis, comprising the steps of:

connecting a vane to a top and a bottom of a fluid-filled sealed container so that the container can rotate freely about the vane via a shaft, the shaft defining an axis of rotation about which the rotation is sensed; and

mounting the vane to a vehicle such that the axis of rotation substantially aligns with an axis of rotation of the vehicle for which rotation is to be sensed.

32. The method recited in claim 31, further comprising the step of imbalancing the vane.

33. The method recited in claim 31, wherein the vane diffusely scatters light by reflection, further comprising the steps of:

illuminating the vane using a light source;

detecting light reflecting from the vane as a first light intensity measurement in a first light detector;

detecting light reflecting from the vane as a second light intensity measurement in a second light detector; and

determining an angle of rotation using the first and second light intensity measurements.

34. The method recited in claim 31, wherein the vane diffusely scatters light by reflection, further comprising the steps of:

illuminating the vane using a first light source;

illuminating the vane using a second light source;

detecting light reflecting from the vane as a light intensity measurement, wherein light reflecting from the vane due to illumination by the first light source is a first intensity measurement and light reflecting from the vane due to the second light source is a second intensity measurement;

alternating illumination of the vane by the first and second light sources; and

determining a rotation angle using the first and second light intensity measurements.

35. The method recited in claim 31, wherein the vane diffusely scatters light by reflection, further comprising the steps of:

illuminating the vane using a light source;

detecting light reflecting from the vane as a light intensity measurement; and

determining a rotation angle using the light intensity measurement.

36. The method recited in claim 31, wherein the vane has a hole, further comprising the steps of:

transmitting light through the hole;

detecting light transmitted through the hole as a light intensity measurement; and

determining a rotation angle using the light intensity measurement.

37. The method recited in claim 31, further comprising:

fixably attaching a cam to the vane;

placing one or more pairs of electrodes around the vane, each pair having a first electrode on one side of the cam, and a second electrode on another side of the cam;

connecting a current source across each pair of electrodes; and

determining a rotation angle using an impedance measurable across each electrode pair.

38. The rotation sensor recited in claim 31, further comprising:

fixably attaching a fiber optic cable to the vane to form a loop;

sending a light pulse through one end o the fiber optic cable;

optically detecting light intensity returning at the other end of the cable; and

determining rotation angle based on the light intensity.