System and method for monitoring piezoelectric material performance

• US 7,262,543 B2
• Filed: 09/08/2004
• Issued: 08/28/2007
• Est. Priority Date: 09/08/2004
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Shams, Qamar A., Moses, Robert W., Chattin, Richard L.
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US10/943,655
• Publication Number:
  US 20060049833A1
• Time in Patent Office: 1,084 Days
• Field of Search: 310/316.01,317,319,311
• US Class Current: 310/316.01
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01R 29/22 Measuring piezoelectric properties

Abstract

A system and method are provided for monitoring performance capacity of a piezoelectric material that may form part of an actuator or sensor device. A switch is used to selectively electrically couple an inductor to the piezoelectric material to form an inductor-capacitor circuit. Resonance is induced in the inductor-capacitor circuit when the switch is operated to create the circuit. The resonance of the inductor-capacitor circuit is monitored with the frequency of the resonance being indicative of performance capacity of the device'"'"'s piezoelectric material.

Claims

1. A system for monitoring performance capacity of a piezoelectric material, comprising:

a piezoelectric material;

an inductor;

switch means coupled to said inductor and operable to selectively (i) electrically couple said inductor to said piezoelectric material wherein an inductor-capacitor circuit is formed with said piezoelectric material forming a capacitor in said inductor-capacitor circuit, and (ii) electrically decouple said inductor from said piezoelectric material;

means for inducing resonance in said inductor-capacitor circuit; and

means for monitoring said resonance wherein a frequency of said resonance is indicative of performance capacity of said piezoelectric material.

2. A system as in claim 1 wherein said piezoelectric material is adapted to be coupled to a power source, and wherein said system further comprises second switch means adapted to be coupled between said power source and said piezoelectric material, said second switch means operable to (i) electrically decouple said power source from said piezoelectric material prior to a time when said resonance is to be monitored, and (ii) electrically couple said power source to said piezoelectric material after said resonance has been monitored.

3. A system as in claim 1 wherein said piezoelectric material is adapted to be coupled to a signal conditioner, and wherein said system further comprises second switch means adapted to be coupled between said signal conditioner and said piezoelectric material, said second switch means operable to (i) electrically decouple said signal conditioner from said piezoelectric material prior to a time when said resonance is to be monitored, and (ii) electrically couple said signal conditioner to said piezoelectric material after said resonance has been monitored.

4. A system as in claim 1 wherein said inductor comprises a spiraled wire.

5. A system as in claim 1 wherein said switch means is remotely controllable.

6. A system as in claim 2 wherein said switch means and said second switch means are remotely controllable.

7. A system as in claim 3 wherein said switch means and said second switch means are remotely controllable.

8. A system as in claim 1 wherein said means for inducing comprises a radio frequency generator.

9. A system as in claim 1 wherein said means for monitoring comprises a radio frequency receiver.

10. A system as in claim 1 wherein said means for inducing and said means for monitoring comprise a radio frequency (RF) transceiver for generating RF energy to induce said resonance and for receiving RF energy resulting from said resonance.

11. A system as in claim 1 wherein said means for monitoring comprises:

means for archiving a plurality of measurements of said frequency taken over a period of time; and

means for comparing said plurality of measurements to monitor changes in said frequency associated therewith.

12. A method of monitoring performance capacity of a piezoelectric material, comprising the steps of:

coupling an inductor to a piezoelectric material wherein an inductor-capacitor circuit is formed with said piezoelectric material forming a capacitor in said inductor-capacitor circuit;

inducing resonance in said inductor-capacitor circuit;

monitoring a frequency of said resonance;

decoupling said inductor from said piezoelectric material; and

repeating said steps of coupling, inducing, monitoring and decoupling wherein changes in said frequency are indicative of changes in performance capacity of said piezoelectric material.

15. A method according to claim 12 wherein said step of inducing comprises the step of transmitting radio frequency (RF) energy from a first location that is remote with respect to said inductor-capacitor circuit.

16. A method according to claim 15 wherein said step of monitoring comprises the step of receiving RF energy resulting from said resonance at a second location that is remote with respect to said inductor-capacitor circuit.

17. A method according to claim 16 wherein said first location and said second location are co-located with one another.

18. A method according to claim 12 wherein said step of repeating occurs at regular intervals.

19. A method according to claim 12 wherein said step of repeating occurs at irregular intervals.

13. A method of monitoring performance capacity of a piezoelectric material, comprising the steps of:

coupling an inductor to a piezoelectric material wherein an inductor-capacitor circuit is formed with said piezoelectric material forming a capacitor in said inductor-capacitor circuit;

inducing resonance in said inductor-capacitor circuit;

monitoring a frequency of said resonance;

decoupling said inductor from said piezoelectric material; and

repeating said steps of coupling, inducing, monitoring and decoupling wherein changes in said frequency are indicative of changes in performance capacity of said piezoelectric material;

wherein said piezoelectric material has a power source coupled thereto, and wherein said method further comprises the step of decoupling said power source from said piezoelectric material prior to said step of monitoring.

14. A method of monitoring performance capacity of a piezoelectric material, comprising the steps of:

coupling an inductor to a piezoelectric material wherein an inductor-capacitor circuit is formed with said piezoelectric material forming a capacitor in said inductor-capacitor circuit;

inducing resonance in said inductor-capacitor circuit;

monitoring a frequency of said resonance;

decoupling said inductor from said piezoelectric material; and

repeating said steps of coupling, inducing, monitoring and decoupling wherein changes in said frequency are indicative of changes in performance capacity of said piezoelectric material;

wherein said piezoelectric material has a signal conditioner coupled thereto, and wherein said method further comprises the step of decoupling said signal conditioner from said piezoelectric material prior to said step of monitoring.

20. A system for monitoring performance capacity of a device that includes one of a power source and a signal conditioner coupled to a piezoelectric material, comprising:

an inductor;

first switch means coupled to said inductor and adapted to be coupled to said piezoelectric material, said first switch means operable to selectively (i) electrically couple said inductor to said piezoelectric material wherein an inductor-capacitor circuit is formed with said piezoelectric material forming a capacitor in said inductor-capacitor circuit, and (ii) electrically decouple said inductor from said piezoelectric material;

second switch means adapted to be coupled between said piezoelectric material and one of said power source and said signal conditioner, said second switch means operable to electrically couple and decouple said piezoelectric material from said one of said power source and said signal conditioner;

means for inducing resonance in said inductor-capacitor circuit; and

means for monitoring said resonance when said second switch means is operated to decouple said piezoelectric material from said one of said power source and said signal conditioner, wherein a frequency of said resonance is indicative of performance capacity of said device.

21. A system as in claim 20 wherein said means for inducing comprises a radio frequency generator.

22. A system as in claim 20 wherein said means for monitoring comprises a radio frequency receiver.

23. A system as in claim 20 wherein a plurality of said devices are to be monitored simultaneously with each of said devices having (i) one said inductor, (ii) one said first switch means, and (iii) one said second switch means associated therewith, such that a plurality of inductor-capacitor circuits are formed when each said first switch means electrically couples a corresponding one said inductor to a corresponding one said piezoelectric material, each said inductor having an inductance such that each of said plurality of inductor-capacitor circuits has a unique resonance frequency associated therewith that is indicative of an acceptable level of performance capacity of a corresponding one of said devices, wherein said means for inducing comprises a radio frequency (RF) generator for generating RF energy across a frequency band that encompasses each said unique resonance frequency of said plurality of inductor-capacitor circuits.

24. A system as in claim 23 wherein said means for monitoring comprises:

an RF receiver for receiving each said resonance at its corresponding frequency; and

means coupled to said RF receiver for generating a spectral map using each said resonance at first and second points in time, wherein changes between said spectral map associated with said first point in time and said spectral map associated with said second point in time at each said unique resonance frequency are indicative of changes in performance capacity of corresponding ones of said devices.

25. A system as in claim 20 wherein said inductor comprises a spiraled wire.

26. A system as in claim 20 wherein said first switch means and said second switch means are remotely controllable.

27. A system for monitoring performance capacity of a piezoelectric device having one of a power source and a signal conditioner coupled thereto, comprising:

a piezoelectric device that includes a piezoelectric material coupled to one of a power source and a signal conditioner;

an inductor;

first switch means coupled to said inductor and said piezoelectric material, said first switch means operable to selectively (i) electrically couple said inductor to said piezoelectric material wherein an inductor-capacitor circuit is formed with said piezoelectric material forming a capacitor in said inductor-capacitor circuit, and (ii) electrically decouple said inductor from said piezoelectric material;

second switch means coupled between said piezoelectric material and one of said power source and said signal conditioner, said second switch means operable to electrically couple and decouple said piezoelectric material from said one of said power source and said signal conditioner;

means for inducing resonance in said inductor-capacitor circuit; and

means for monitoring said resonance when said second switch means is operated to decouple said piezoelectric material from said one of said power source and said signal conditioner, wherein a frequency of said resonance is indicative of performance capacity of said device.

28. A system as in claim 27 wherein said means for inducing comprises a radio frequency generator.

29. A system as in claim 27 wherein said means for monitoring comprises a radio frequency receiver.

30. A system as in claim 27 wherein a plurality of said devices are to be monitored simultaneously with each of said devices having a power source coupled to a piezoelectric material and with each of said devices having (i) one said inductor, (ii) one said first switch means, and (iii) one said second switch means associated therewith, such that a plurality of inductor-capacitor circuits are formed when each said first switch means electrically couples a corresponding one said inductor to a corresponding one said piezoelectric material, each said inductor having an inductance such that each of said plurality of inductor-capacitor circuits has a unique resonance frequency associated therewith that is indicative of an acceptable level of performance capacity of a corresponding one of said devices, wherein said means for inducing comprises a radio frequency (RF) generator for generating RF energy across a frequency band that encompasses each said unique resonance frequency of said plurality of inductor-capacitor circuits.

31. A system as in claim 30 wherein said means for monitoring comprises:

an RF receiver for receiving each said resonance at its corresponding frequency; and

means coupled to said RF receiver for generating a spectral map using each said resonance at first and second points in time, wherein changes between said spectral map associated with said first point in time and said spectral map associated with said second point in time at each said unique resonance frequency are indicative of changes in performance capacity of corresponding ones of said devices.

32. A system as in claim 27 wherein said inductor comprises a spiraled wire.

33. A system as in claim 27 wherein said first switch means and said second switch means are remotely controllable.