Method and system for diagnostics and prognostics of a mechanical system

• US 7,027,953 B2
• Filed: 12/30/2002
• Issued: 04/11/2006
• Est. Priority Date: 12/30/2002
• Status: Expired due to Fees

• Current Assignee: RSL Electronics Ltd.
• Original Assignee: RSL Electronics Ltd.
• Inventors: Klein, Renata
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US10/334,477
• Publication Number:
  US 20050096873A1
• Time in Patent Office: 1,198 Days
• Field of Search: 702/54, 702/56, 702/77, 702/81, 702/122, 702/150, 702182-185, 700/38, 700/279, 700/280, 700/287, 290/408, 701/120, 244/1.N, 340/945, 706/52
• US Class Current: 702/184
• CPC Class Codes: G01H 1/006 of the rotor of turbo machines
• CPC Class Codes: G01M 13/028 Acoustic or vibration analysis
• CPC Class Codes: G05B 23/0275 Fault isolation and identification, e.g. classify fault; estimate cause or root of failure

Abstract

A vibrational analysis system diagnosis the health of a mechanical system by reference to vibration signature data from multiple domains. Features are extracted from signature data by reference to pointer locations. The features provide an indication of signature deviation from a baseline signature in the observed domain. Several features applicable to a desired fault are aggregated to provide an indication of the likelihood that the fault has manifested in the observed mechanical system. The system may also be used for trend analysis of the health of the mechanical system.

Claims

1. A health maintenance system for a mechanical system, comprising:

A vibration sensor, the vibration sensor acquiring vibrational data relating to the mechanical system;

A data processing circuit, the data processing circuit including a transformation module transforming the data acquired by the vibrational sensor to signature data in a plurality of domains, the signature data associated with at least one predetermined pointer location corresponding to known faults of the mechanical system;

A diagnosis circuit, the diagnosis circuit extracting features from the signature data by reference to said pointer location associated each signature data, the data diagnosis module employing at least one index function to provide features corresponding to each pointer location and signature data;

A decision circuit, the decision circuit determining a health status for the mechanical system by reference to the features provided by the diagnosis circuit.

2. The system of claim 1 wherein said mechanical system is an aircraft engine.

3. The system of claim 1 further comprising at least one gas path sensor.

4. A health prognosis method for a mechanical system, the method comprising the steps of:

monitoring at least one operational parameter of said mechanical system;

detecting an anomaly in said operational parameters;

recording at least vibrational data in response to detecting said anomaly;

processing said vibrational data to provide features associated with said mechanical system;

trending said features by a prognosis module to provide an expected future feature data; and

analyzing said future feature data to determine an expected effect on said mechanical system.

5. The method of claim 4 further comprising the step of downloading to at least one communication ground station the data acquired in response to detecting the presence of said anomaly.

6. The method of claim 5 wherein said downloading step via wireless link to said ground stations.

7. The method of claim 5 wherein said downloading step is performed periodically during operation of said mechanical system.

8. The method of claim 5 wherein said downloading step further comprises the step of downloading said anomalies to an off-line data extraction application.

9. The method of claim 4 wherein said recording step includes the recording of an anomaly code indicative of the detected anomaly, and historical data relevant to said anomaly.

10. The method of claim 4 wherein said trending step is triggered by one or more predefined states.

11. The method of claim 4 further comprising the steps of:

computing at least one life usage indicators; and

recording said life usage indicators.

12. A method for providing a health indication for a mechanical system, comprising:

receiving vibrational data from a data collection unit;

processing the vibrational data to provide at least one wide-band frequency-domain signature and at least one other signature in another domain;

extracting feature data from said signatures by reference to pointer locations for the signatures and corresponding index functions, the pointer locations and index functions associated with known faults of the mechanical system; and

comparing the feature data with feature data associated with known system faults to provide a health indication for the mechanical system.

13. A method for diagnosing the health of a mechanical system, the method comprising the steps of:

receiving vibrational data from at least one sensor monitoring the mechanical system;

processing the vibrational data to provide features associated with said mechanical system;

comparing the provided features with features associated with of known fault conditions; and

determining whether a fault condition should be indicated for said mechanical system based on said comparing.

14. A computer implemented health diagnostic system for a mechanical system, comprising:

at least one vibration sensor positioned to collect vibration data of at least one component of said mechanical system;

a data processing circuit, the data processing circuit including a processing unit which transforms the vibration data into signatures in a plurality of domains, each signature data in each domain is associated with at least one pointer, said pointers related to at least one known fault condition of the mechanical system;

a diagnostic circuit, the diagnostic circuit employs an index function of each pointer location to extract feature data from each signature; and

a decision circuit, the decision circuit deriving a health status from said feature data extracted by the diagnosis circuit.

15. The system of claim 14, wherein the vibration sensor is further positioned to collect vibrational data from the exterior of enclosure case of said at least one component of the mechanical system.

16. The system of claim 14, wherein said mechanical system is a rotating machine.

17. The system of claim 16, wherein said mechanical system is an aircraft engine.

18. The system of claim 14, wherein said diagnostic circuit further aggregates features of the same pointer location, across a plurality of domains.

19. The system of claim 14, further comprising at least one non-vibration sensor positioned to collect data associated with the mechanical system.

20. The system of claim 14, wherein said at least one non-vibration sensor is a gas path data sensor for collecting mechanical system gas path data.

21. The system of claim 19, further comprising a storage module adapted to record said vibration and said gas path data.

22. The system of claim 14, further comprising an operator display adapted to communicate an indication of mechanical system health.

23. The system of claim 19, wherein the decision circuit is adapted to receive said gas path data for deriving said health status.

24. The system of claim 14, wherein the diagnostic index function comprises a function for comparing a baseline signature extracted during normal system operation with a signature provided by the data processing circuit.

25. The system of claim 14 wherein said diagnostic circuit further assigns relative weight to each feature data item associated with said known fault condition of the system by a corresponding pointer location.

26. A health prognostic method for a mechanical system, the method comprising:

detecting a deviation of operational data, including vibrational data, from a predetermined normal;

recording at least vibration data in response to detecting said anomaly;

transforming the vibration data into signatures in a plurality of domains;

extracting features from said signatures to provide features that are indicative of a health status of a component of said mechanical system;

trending said extracted features to provide expected future feature data; and

analyzing said future feature data to provide a prognosis of an expected parameter state for said mechanical system.

27. The method of claim 26 further comprising downloading, to at least one communication ground station, the vibration data acquired in response to detecting the presence of said deviation.

28. The method of claim 27 wherein said downloading step is via wireless link to said ground stations.

29. The method of claim 27 wherein said downloading step is performed periodically during operation of said mechanical system.

30. The method of claim 27 wherein said downloading step is performed subsequent to operation of said mechanical system.

31. The method of claim 27 wherein said downloading step further comprises the step of recording said parameter deviation data by an off-line data extraction application.

32. The method of claim 26 wherein said recording step includes the recording of a parameter deviation code indicative of the detected parameter deviation, along with recording data relevant to said parameter deviation.

33. The method of claim 26 wherein said recording step is triggered by one or more predefined system states.

34. The method of claim 26 wherein said trending step employs polynomial fitting to predict said expected parameter state for the mechanical system.

35. The method of claim 26 wherein said trending step employs adaptive reasoning parametric models to predict said expected parameter state for the mechanical system.

36. The method of claim 26 further comprising the steps of:

computing at least one life usage indicator; and

recording said life usage indicator.

37. The method of claim 26, wherein said mechanical system includes at least one inter-shaft bearing, whereby the method detects deterioration of said inter-shaft bearing.

38. A method for providing a health indication for a mechanical system, comprising:

collecting vibration data by a data collection unit;

processing the vibration data to provide at least one wide-band frequency-domain signature and at least one other signature in another domain;

extracting feature data from said signatures by reference to at least one pointer location for the signatures and by employing a corresponding index function, the pointer location and index function associated with known faults of the mechanical system; and

comparing the feature data with feature data associated with known system faults to provide a health indication for the mechanical system.

39. A method for diagnosing the health of a mechanical system, comprising:

collecting vibration data by employing at least one vibration sensor;

deriving vibration signatures in multiple domains by transforming the vibration data to multiple domains;

extracting data from each signature by reference to predetermined pointer data;

employing an index function to extract feature data from the vibration signatures in the various domains by comparing said extracted data to baseline data associated with the index function;

aggregating feature data associated with a known fault;

comparing said feature data to a predetermined threshold to diagnose the health of the mechanical system.

40. The method of claim 39, wherein said pointer data defines at least one domain region applicable to a known system fault.

41. The method of claim 40, wherein the pointer data defined region is compared to a baseline region by using diagnostic indices.

42. The method of claim 39, wherein each index provides feature data by reference to deviation of the pointer defined region from the same region of baseline data.

43. The method of claim 39, further comprising aggregating the feature data to arrive at a health diagnosis for the mechanical system.

44. The method of claim 43, wherein said aggregating further includes combining the extracted features with features from gas path data.

45. The method of claim 39, further comprising predicting failures of the mechanical system by comparing the extracted features to historical data relating to known faults.

46. The method of claim 39, wherein said domains are selected from the group consisting of time, order, quefrency, time-frequency response, amplitude, parameters, rotations per second, RPS-order, cycles, envelope, phase average, orders of envelope, cepstrum of envelope, and background spectra in the frequency domain.

47. The method of claim 39, wherein said signature analysis is wideband from 0 to 5 KHz.