Volume measurement system and method for volume element counting

• US 6,516,661 B1
• Filed: 01/28/1999
• Issued: 02/11/2003
• Est. Priority Date: 01/28/1999
• Status: Expired due to Fees

• Current Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Massimo, Maurizio, Spillman, William Bert Jr.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): CYGAN, MICHAEL T
• Application Number:
  US09/239,468
• Time in Patent Office: 1,475 Days
• Field of Search: 731/49, 733/04.C, 732/90.R, 732/92, 340/618, 340/620
• US Class Current: 73/149
• CPC Class Codes: G01F 23/802 Particular electronic circuits for digital processing equipment
• CPC Class Codes: G01F 23/804 containing circuits handling parameters other than liquid level

Abstract

A volume measurement system uses volume element counting in determining the amount of a liquid such as fuel in an irregularly-shaped container such as a fuel tank which can have changing orientation. The container is conceptually divided up into a plurality of volume elements. An orientation sensor determines the orientation of the container or of the liquid surface, which is approximated as a plane. A computational or optical processor uses orientation data to project vectors representing the volume elements onto a direction normal to the liquid interface plane. These projected distances are then arithmetically or optically compared to the location of the liquid interface plane.

Claims

1. A liquid volume measurement system, comprising:

an orientation sensor to sense an orientation of a liquid surface within a container;

a liquid level sensor to sense a level of the liquid surface; and

a processor operatively coupled to the orientation sensor for receiving orientation data, and operatively coupled to the liquid level sensor for receiving level data;

wherein the processor uses the orientation data and the level data to generate an indication of the surface location, and

wherein for each of a plurality of volume elements into which the container is divided, the processor compares an indication of a volume element location of the respective element with the indication of the surface location of the liquid surface.

26. The system of claim 1, further comprising a display for displaying the amount of the liquid in the container.

27. The system of claim 1, wherein the container is a fuel tank and the liquid is fuel.

28. A liquid mass measurement system comprising the liquid volume measurement system of claim 1 and a densitometer operatively coupled to the liquid volume measurement system for converting volume measurements to mass measurements.

2. A liquid volume measurement system comprising:

an orientation sensor to sense an orientation of a liquid surface within the container;

a liquid level sensor to sense a level of the liquid surface relative to the container; and

a processor operatively coupled to the orientation sensor for receiving orientation data, and operatively coupled to the liquid level sensor for receiving level data;

wherein the processor uses the orientation data and the level data to generate an indication of the surface location,

wherein for each of a plurality of volume elements of the container, the processor compares an indication of a volume element location of the respective element with the indication of the surface location of the liquid surface,

wherein the indication of a volume element location is an indication of a volume element distance of the respective element along an axis normal to the liquid surface, and

wherein the indication of a surface location is an indication of a level distance of the surface along the axis.

3. The system of claim 2, wherein the indication of the volume element distance is an indication of a randomly-chosen point within the volume element.

4. The system of claim 2, wherein the processor further counts the volume elements having volume element distances less than the level distance and divides the count by the number of the volume elements.

5. The system of claim 2, further comprising a storage device operatively coupled to the processor, the storage device storing location data for each of the volume elements.

6. The system of claim 5, wherein the processor includes an optical filter, the optical filter storing location data for each of the volume elements, and wherein the processor optically combines the filter with an optical element representing the orientation of the container.

7. The system of claim 5, wherein the storage device is a computer memory device.

8. The system of claim 2, wherein the processor includes a computational processor, and the indication of the element distance for a respective element of the volume elements is a number.

9. The system of claim 8, wherein the number is the dot product of coordinates of the respective element and coordinates of a vector normal to the liquid surface.

10. The system of claim 2, wherein the processor includes an optical processor.

11. The system of claim 10, wherein the optical processor includes a light-producing section which outputs light in a plurality of light areas, and a light detector which detects light output by the light-producing section, wherein light in each of the areas corresponds to respective of the volume element distances along the axis.

12. The system of claim 11, wherein the light-producing section includes a white light, an optical container filter which encodes location data for the volume elements as absorption areas, and a programmable orientation filter which filters components of incident light by an amount which corresponds to the orientation of the liquid surface.

13. The system of claim 11, wherein the light-producing section includes a programmable colored light, the color of the colored light being a function of the orientation of the liquid surface, and an optical container filter which encodes location data for the volume elements as absorption areas.

14. The system of claim 11, wherein the light-producing section includes a programmable colored light, the color of the colored light in each of the areas being a function of respective of the volume elements, and a programmable orientation filter which filters components of incident light by an amount which corresponds to the orientation of the liquid surface.

15. The system of claim 11, wherein the light detector is a color camera.

16. The system of claim 15, wherein the optical processor further includes a comparator which for each of the areas compares a light intensity for light in each of the light areas with a value corresponding to the indication of a level distance of the surface along the axis.

17. The system of claim 16, wherein the optical processor further includes an accumulator.

18. The system of claim 11, wherein the light detector is a photodetector and the optical processor further includes a programmable active threshold optical filter which selectively absorbs light from each of the light areas based on whether the intensity of the light exceeds a threshold which is a function of the level distance of the liquid surface along the axis.

19. The system of claim 2, wherein the liquid level sensor includes an ultrasonic sensor.

20. The system of claim 2, wherein the liquid level sensor includes at least one capacitance probe.

21. The system of claim 2, wherein the liquid level sensor includes at least two capacitance probes, with measurements from the at least two capacitance probes being used to determine the dielectric constant of the liquid.

22. The system of claim 2, wherein the orientation sensor includes an accelerometer.

23. The system of claim 22, wherein the accelerometer is a three-axis accelerometer.

24. The system of claim 2, wherein the orientation sensor includes at least three capacitance probes.

25. The system of claim 24, wherein the liquid level sensor includes at least one of the at least three capacitance probes.

29. A method for measuring liquid volume, comprising the steps of:

conceptually dividing a container into a plurality of volume elements;

representing each of the volume elements by an associated point within the respective element, wherein for each of the volume elements there exists an associated vector between a fixed point and the respective associated point;

determining a vector normal to a liquid surface within the container;

determining a liquid surface distance between the fixed point and the liquid surface in the direction of the normal vector;

projecting the associated vectors in the direction of the normal vector to determine a projected distance for each of the volume elements; and

comparing each of the projected distances with the liquid surface distance.

30. The method of claim 29, further comprising counting the projected distances which are less than the liquid surface distance and dividing by the number of the volume elements.

31. The method of claim 29, further comprising displaying a representation of the amount of a liquid in the container.

32. The method of claim 29, wherein the representing each of the volume elements by an associated point includes randomly choosing the location of the associated point with the respective element.

33. The method of claim 29, wherein the determining a liquid surface distance includes sensing the liquid surface distance using an ultrasonic transducer.

34. The method of claim 29, wherein the determining a unit vector normal includes sensing the orientation of the container using an acceleration transducer.

35. The method of claim 29, wherein the projecting includes calculating the dot product of the associated vectors and the normal vector.

36. The method of claim 29, wherein the projecting includes optically combing optical analogs of the associated vectors and the normal vector.

37. The method of claim 29, wherein the determining a unit vector normal includes sensing the orientation of the container, wherein the determining a liquid surface distance includes using measurements from two or more partially-covered capacitance probes to determine a dielectric constant of the liquid.

38. The method of claim 29, further comprising determining a density of the liquid and using the density to convert volume measurements to mass measurements.

39. A fuel volume measurement system, comprising:

an orientation sensor to sense an orientation of a fuel surface.within a fuel tank;

a fuel level sensor to sense a level of the fuel surface; and

a processor operatively coupled to the to the orientation sensor for receiving orientation data, and operatively coupled to the fuel level sensor for receiving the level;

a storage device operatively coupled to the processor, the storage device storing location data for each of a plurality of volume elements;

wherein for each of the volume elements of the fuel tank, the processor compares an indication of a volume element distance of the respective element along an axis normal to the fuel surface with an indication of a level distance of the surface along the axis, and wherein the processor further counts the volume elements having volume element distances less than the level distance and divides the count by the number of the volume elements.

40. The system of claim 39, wherein the processor includes a computational processor, and the indication of the element distance for a respective element of the volume elements is a number.

41. The system of claim 39, wherein the processor includes an optical processor.

42. A fuel mass measurement system comprising the fuel volume measurement system of claim 39 and a densitometer operatively coupled to the liquid volume measurement system for converting volume measurements to mass measurements.

43. A liquid volume measurement system, comprising:

sensor means for determining the orientation of a liquid surface within a container and the position of the liquid surface along an axis normal to the liquid surface; and

processor means for projecting a plurality of volume elements into which the container is divided, onto said axis for comparison with the position of the liquid surface along said axis.

44. A system as set forth in claim 43, wherein the sensor means includes a non-invasive sensor for determining the orientation of the liquid surface.

45. A system as set forth in claim 44, wherein said non-invasive sensor is an ultrasonic transducer.