Radio frequency tank eigenmode sensor for propellant quantity gauging

• US 8,353,209 B1
• Filed: 09/30/2009
• Issued: 01/15/2013
• Est. Priority Date: 09/30/2009
• Status: Expired due to Fees

• Current Assignee: Nasa Headquarters, NASA The United States Government As Represented By The Administrator of
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Zimmerli, Gregory A.
• Primary Examiner(s): ROGERS, DAVID A
• Application Number:
  US12/570,841
• Time in Patent Office: 1,203 Days
• Field of Search: 732/90.B, 732/90.R, 732/90.V, 732/91, 733/04.R
• US Class Current: 73/290.B
• CPC Class Codes: G01F 22/00 Methods or apparatus for measuring volume of fluids or fluent solid material, not otherwise provided for
• CPC Class Codes: G01F 23/284 Electromagnetic waves

Abstract

A method for measuring the quantity of fluid in a tank may include the steps of selecting a match between a measured set of electromagnetic eigenfrequencies and a simulated plurality of sets of electromagnetic eigenfrequencies using a matching algorithm, wherein the match is one simulated set of electromagnetic eigenfrequencies from the simulated plurality of sets of electromagnetic eigenfrequencies, and determining the fill level of the tank based upon the match.

Claims

1. A method for measuring the quantity of fluid in a tank comprising the steps of:

simulating a plurality of sets of electromagnetic eigenfrequencies of the tank for a range of fill levels using an electromagnetic eigenmode solver algorithm, wherein each simulated set of electromagnetic eigenfrequencies represents a specific fill level within the tank;

inputting the simulated plurality of sets of electromagnetic eigenfrequencies into a computer database;

transmitting a first range of radio waves using a transmitting device located inside the tank;

receiving the first range of radio waves using a receiving device located inside the tank;

identifying a measured set of electromagnetic eigenfrequencies in the first range of radio waves using an eigenfrequency identifier algorithm;

comparing the measured set of electromagnetic eigenfrequencies to the simulated plurality of sets of electromagnetic eigenfrequencies;

selecting a match between the measured set of electromagnetic eigenfrequencies and the simulated plurality of sets of electromagnetic eigenfrequencies using a matching algorithm, wherein the match is one simulated set of electromagnetic eigenfrequencies from the simulated plurality of sets of electromagnetic eigenfrequencies;

determining the fill level of the tank based upon the match.

2. The method of claim 1 wherein each simulated set of electromagnetic eigenfrequencies represents a specific fluid configuration at a specific fill level within the tank, and wherein the fluid has at least one fluid configuration at each specific fluid fill level of the tank.

3. The method of claim 1 wherein the tank further comprises a metal liner.

4. The method of claim 1 wherein the tank is formed of metal.

5. The method of claim 1 wherein before the step of transmitting a first range of radio waves, the method further comprises the step of:

placing the tank in a low gravity environment.

6. The method of claim 1 wherein an antenna comprises the transmitting device.

7. The method of claim 1 wherein an antenna comprises the receiving device.

8. The method of claim 1 wherein the fluid is a dielectric fluid.

9. The method of claim 1 wherein the fluid is a cryogenic propellant.

10. The method of claim 1 wherein the eigenfrequency identifier algorithm includes a peak-detection algorithm for identifying the peaks in the first range of radio waves.

11. The method of claim 1 wherein a single antenna comprises the transmitting device and the receiving device.

12. The method of claim 1 wherein the matching algorithm includes a correlation function for determining the match between the measured set of electromagnetic eigenfrequencies and the one simulated set of electromagnetic eigenfrequencies.

13. The method of claim 1 wherein the range of fill levels is from about 0% to about 100%.

14. The method of claim 1 wherein the step of simulating a first set of electromagnetic eigenfrequencies further comprises simulating the first set of electromagnetic eigenfrequencies for the range of fill levels in about 1% increments.

15. A method for measuring the quantity of fluid in a tank comprising the steps of:

simulating a plurality of sets of electromagnetic eigenfrequencies of the tank for a range of fill levels using an electromagnetic eigenmode solver algorithm, wherein each simulated set of electromagnetic eigenfrequencies represents a specific fill level within the tank;

inputting the simulated plurality of sets of simulated electromagnetic eigenfrequencies into a computer database;

transmitting a first range of radio waves using a first transmitting device located inside the tank;

receiving the first range of radio waves using a first receiving device located inside the tank;

identifying a first measured set of electromagnetic eigenfrequencies in the first range of radio waves using an eigenfrequency identifier algorithm;

transmitting a second range of radio waves using a second transmitting device located inside the tank;

receiving the second range of radio waves using the second receiving device located inside the tank;

identifying a second measured set of electromagnetic eigenfrequencies in the second range of radio waves using an eigenfrequency identifier algorithm;

combining the first measured set of electromagnetic eigenfrequencies with the second measured set of electromagnetic eigenfrequencies into a combined measured set of electromagnetic eigenfrequencies;

comparing the combined measured set of electromagnetic eigenfrequencies to the simulated plurality of sets of electromagnetic eigenfrequencies;

selecting a match between the combined measured set of electromagnetic eigenfrequencies and the simulated plurality of sets of electromagnetic eigenfrequencies using a matching algorithm, wherein the match is one simulated set from the simulated plurality of sets of electromagnetic eigenfrequencies;

determining the fill level of the tank based upon the match.

16. The method of claim 15 wherein a first antenna comprises the first transmitting device and the first receiving device, and wherein a second antenna comprises the second transmitting device and the second receiving device.

17. The method of claim 15 wherein the step of simulating a plurality of sets of electromagnetic eigenfrequencies further comprises simulating the plurality of sets of electromagnetic eigenfrequencies for the range of fill levels from about 0% to about 100% in about 1% increments.

18. An apparatus for measuring a quantity of fluid comprising:

a tank;

a simulator device comprising an eigenmode solver computer algorithm for simulating a plurality of sets of electromagnetic eigenfrequencies of the tank for a range of fill levels, wherein each simulated set of electromagnetic eigenfrequencies represents a specific fill level within the tank;

an electronic data storage device for storing the simulated plurality of sets of electromagnetic eigenfrequencies;

a transmitter device located inside the tank for transmitting a first range of radio waves;

a receiver device located inside the tank for receiving the first range of radio waves;

an identifier device comprising an eigenfrequency identifier computer algorithm for identifying a measured set of electromagnetic eigenfrequencies in the first range of radio waves;

a comparer device for comparing the measured set of electromagnetic eigenfrequencies to the simulated plurality of sets of electromagnetic eigenfrequencies;

a selector device for selecting a match between the measured set of electromagnetic eigenfrequencies and the simulated plurality of sets of electromagnetic eigenfrequencies using a matching computer algorithm, wherein the match is one simulated set from the simulated plurality of sets of electromagnetic eigenfrequencies; and

a determiner device for determining the fill level of the tank based upon the match.

19. The method of claim 18 wherein the tank further comprises a metal liner.

20. The method of claim 18 wherein an antenna comprises the transmitting device and the receiving device.