Self-calibrating pressure sensor

• US 20080041164A1
• Filed: 10/27/2006
• Published: 02/21/2008
• Est. Priority Date: 10/27/2005
• Status: Active Grant

• Current Assignee: Advanced Research Corporation
• Original Assignee: Advanced Research Corporation
• Inventors: Wagner, Gregory, Cottles, Vernon
• Granted Patent: US 7,543,501 B2
• Time in Patent Office: Days
• US Class Current: 73/726
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect

Abstract

The present invention is system and method for providing a self-calibrating pressure sensor. A pressure sensor apparatus comprises a diaphragm, at least one driving element operably coupled to the diaphragm configured to induce deflection in the diaphragm, and at least one strain gauge coupled to the diaphragm. The at least one strain gauge measures the deflection of the diaphragm. Typically, the driving elements will be piezoelectric drivers and will be operably coupled to the diaphragm. A method for evaluating a pressure sensor comprises inducing deflection in a diaphragm, measuring the deflection, determining the frequency-dependent response, calculating mechanical characteristics of the diaphragm from the frequency-dependent response, and calculating a response coefficient for the diaphragm based in part on said mechanical characteristics. The response coefficient is used to evaluate the sensor. The sensor can then be re-calibrated or self-calibrated based on the response coefficient.

Claims

1. A pressure sensor comprising:

a diaphragm;

at least one driving element operably coupled to the diaphragm, wherein the at least one driving element is configured to induce deflection in the diaphragm; and

at least one strain gauge coupled to the diaphragm, wherein the at least one strain gauge measures the deflection of the diaphragm.

2. The pressure sensor of claim 1, wherein the at least one driving element is a piezoelectric driver.

3. The pressure sensor of claim 1, wherein the at least one driving element is operably coupled to the diaphragm to induce vibrations in the diaphragm.

4. The pressure sensor of claim 1, wherein the at least one strain gauge is positioned on the diaphragm to distinguish resonant behavior of the diaphragm.

5. The pressure sensor of claim 1, wherein the geometry of the diaphragm is such that it promotes specific frequency responses of the diaphragm.

6. The pressure sensor of claim 1, wherein the at least one driving element is configured to induce resonant response behavior in the diaphragm.

7. The pressure sensor of claim 1, wherein the at least one driving element is configured to provide an impulse excitation to the diaphragm.

8. A method for evaluating a pressure sensor, comprising:

inducing deflection in a diaphragm;

measuring the deflection in the diaphragm;

determining the frequency-dependent response of the diaphragm;

calculating mechanical characteristics of the diaphragm from the frequency-dependent response; and

calculating a response coefficient for the diaphragm based in part on the mechanical characteristics of the diaphragm, wherein the response coefficient is used to evaluate the sensor.

9. The method of claim 8, wherein determining the frequency-dependent response of the diaphragm comprises determining the resonant frequencies in the diaphragm.

10. The method of claim 8, wherein determining the frequency-dependent response of the diaphragm comprises, determining decay of characteristic frequency modes of the diaphragm.

11. The method of claim 8, wherein piezoelectric drivers that are operably coupled to the diaphragm are used to induce deflection in the diaphragm.

12. The method of claim 11, wherein inducing deflection in a diaphragm comprises inducing deflection in a diaphragm with a self-resonating oscillation loop.

13. The method of claim 8, wherein determining the frequency-dependent response of the diaphragm further comprises determining fundamental modes of oscillation of the diaphragm with at least one strain gauge strategically placed on the diaphragm.

14. The method of claim 8, wherein the geometry of the diaphragm is such that it promotes specific frequency responses of the diaphragm.

15. The method of claim 8, further comprising re-calibrating the sensor.

16. The method of claim 8, further comprising self-calibrating the sensor.

17. The method of claim 8, further comprising determining the operable functionality of the sensor.

18. The method of claim 17, further comprising detecting failure of the sensor.

19. A method for evaluating a pressure sensor, comprising:

creating fundamental modes of oscillation in a diaphragm using at least two driving elements, wherein a relative driving phase between the at least two driving elements controls the fundamental modes;

calculating mechanical characteristics of the diaphragm from the fundamental modes; and

calculating a response coefficient for the diaphragm based in part on the mechanical characteristics of the diaphragm, wherein the response coefficient is used to evaluate the sensor.

20. The method of claim 19, wherein the at least two driving elements are piezoelectric drivers.