Ultrasensitive surveillance of sensors and processes

• US 6,202,038 B1
• Filed: 08/12/1999
• Issued: 03/13/2001
• Est. Priority Date: 01/14/1998
• Status: Expired due to Term

• Current Assignee: ARCH Development Corporation (University of Chicago)
• Original Assignee: ARCH Development Corporation (University of Chicago)
• Inventors: Jarman, Kristin K., Wegerich, Stephan W., Gross, Kenneth C.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Bui, Bryan
• Application Number:
  US09/373,326
• Time in Patent Office: 579 Days
• Field of Search: 702/179, 702/182-185, 702/188, 706/914, 706/915, 376/215, 376/216
• US Class Current: 702/183
• CPC Class Codes: G21C 17/00 Monitoring; Testing measuring in general G01; Maintaining
• CPC Class Codes: G21D 3/001 Computer implemented control
• CPC Class Codes: Y02E 30/00 Energy generation of nuclear origin
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

A method and apparatus for monitoring a source of data for determining an operating state of a working system. The method includes determining a sensor (or source of data) arrangement associated with monitoring the source of data for a system, activating a method for performing a sequential probability ratio test if the data source includes a single data (sensor) source, activating a second method for performing a regression sequential possibility ratio testing procedure if the arrangement includes a pair of sensors (data sources) with signals which are linearly or non-linearly related; activating a third method for performing a bounded angle ratio test procedure if the sensor arrangement includes multiple sensors and utilizing at least one of the first, second and third methods to accumulate sensor signals and determining the operating state of the system.

Claims

1. A method of monitoring a source of data for determining an operating condition of a selected system, comprising the steps of:

providing reference data characteristic of an operating condition of a reference system;

collecting selected data from said source of data and which is characteristic of an operating condition of a selected system;

performing a bounded angle ratio test procedure on said reference data and said selected data to determine whether there is a deviation of said selected data for said selected system relative to said reference data of said reference system; and

generating an indication upon determining the deviation.

2. The method as defined in claim 1 wherein the deviation is an item selected from the group consisting of said selected system and the source of the data.

3. The method as defined in claim 2 wherein the source of the data comprises at least one of a sensor and a data base.

4. The method as defined in claim 1 wherein said indication comprises an alarm signal.

5. The method as defined in claim 1 wherein the step of performing a bounded angle ratio test procedure comprises comparing;

a first angle in a first triangle having a base opposite said first angle with a length along said base proportional to the difference between corresponding values comprised of a value of said selected data and a value in said reference data, to a second angle in a second triangle having a base opposite said second angle with a length proportional to the range over all values in said reference data.

6. The method as defined in claim 5 wherein the first and second triangles share a common altitude line segment.

7. The method as defined in claim 1 wherein the step of determining a deviation of said selected data relative to said reference data includes calculating a similarity angle.

8. The method as defined in claim 1 wherein the selected data from the source of data is being processed in substantially real time.

9. The method as defined in claim 1 wherein the selected data from the source of data are derived at least in part from previously accumulated data.

10. The method as defined in claim 1 wherein the method includes another step of performing a sequential probability ratio test on said selected data characteristic of the operating condition of the selected system.

11. An apparatus for monitoring a data source for determining a selected operating condition of a monitored system, comprising:

at least one first computer module operative to provide at least one of

(a) reference data characteristic of a reference operational condition of a model system and

(b) selected data characteristic of an operating condition of a selected system;

a second computer module operative to perform a similarity angle analysis on said reference data and said selected data for determining similarity angle data characteristic of a similarity value; and

a third computer program module operative to receive and operate on the similarity value to determine whether a deviation exists for the monitored system relative to the model system.

12. The apparatus as defined in claim 11 wherein the reference operational condition of the model system comprises a normal operating condition.

13. The apparatus as defined in claim 11 wherein said third computer program module includes a computer program which performs a sequential probability ratio test on the similarity angle data.

14. The apparatus as defined in claim 11 wherein said similarity angle analysis of said second module computer program comprises a bounded angle ratio test to determine a similarity angle characteristic of the operating condition of the monitored system relative to the operational condition of the model system.

15. The apparatus as defined in claim 14 wherein the bounded angle ratio test includes a computer program to establish a reference point R positioned adjacent a similarity domain line characteristic of a similarity domain with the point R at a distance h of closest approach to said similarity domain line.

16. The apparatus as defined in claim 15 wherein the second computer module establishes a minimum value X_min and a maximum value X_max over a statistical distribution over the similarity domain.

17. The apparatus as defined in claim 16 wherein a line from the reference point R to said similarity domain intersects at point X_med, a median over all corresponding values in said reference data.

18. The apparatus as defined in claim 17 wherein an angle defined by lines from the reference point R to the values X_min and X_max is 90°

.

19. The apparatus as defined in claim 18 wherein the similarity angle is defined by:

θ

=arc tan(X₁/h)−

arc tan(X₀/h), where X₁ is a larger value and X₀ is a smaller value in a set formed by a first value from said selected data and a second corresponding value selected from said reference data.

20. The apparatus as defined in claim 11 wherein the data source comprises at least two sources of data and said first computer module includes a computer program which operates to monitor at least two sources of data separately when the at least two sources of data are uncorrelated.

21. The apparatus as defined in claim 11 wherein the data source comprises at least two sources of data and said at least one first computer module includes a computer program which operates to monitor said at least two sources of data and perform a regression analysis on the similarity angle data.

22. The apparatus as defined in claim 21 wherein the regression analysis comprises a sequential probability ratio test.

23. The apparatus as defined in claim 11 wherein the similarity angle data is used in a computer program to compute estimated data characteristic of the operating condition of said selected system.

24. The apparatus as defined in claim 11 wherein a source of estimated data for the selected system is provided from a preaccumulated data source based upon determining a sensor of the data source has malfunctioned.

25. The apparatus as defined in claim 24 wherein the data source derives from a plurality of individual sources of data which provide signals selected from the group of non-linearly and linearly related signals.

26. A method of monitoring a source of data for determining an operating condition of a selected system relative to a reference system, comprising the steps of:

providing reference data characteristic of an operating condition of a reference system;

collecting selected data from a source of data with said selected data characteristic of an operating condition of a selected system;

performing a bounded angle ratio test procedure on said reference data and said selected data to determine a measure of similarity of said selected data for said selected system relative to said reference data of said reference system; and

analyzing said measure of similarity to determine the operating condition of said selected system relative to said reference system.

27. A method according to claim 26 further comprising the step of generating an estimate of said selected data based on said measure of similarity.

28. A method according to claim 26 further comprising the step of performing a statistical hypothesis test on said selected data and said estimate thereof, to determine if there is a statistically significant deviation between them.

29. A method according to claim 28 wherein said statistical hypothesis test comprises a sequential probability ratio test.

30. The method as defined in claim 26 further including the step of carrying out an action responsive to analyzing said measure of similarity.

31. An apparatus for monitoring an operating condition of a selected system relative to a reference system, comprising:

a first data source for providing reference data characteristic of an operating condition of a reference system;

a second data source for providing selected data characteristic of an operating condition of a selected system; and

a computer module operative to perform a bounded angle ratio test procedure on said reference data and said selected data to determine a measure of similarity of said selected data for said selected system relative to said reference data of said reference system and further operative to analyze a deviation of the selected system from the reference system, thereby enabling a user to act responsive to any said deviation.

32. An apparatus according to claim 31 further comprising a computer module operative to generate an estimate of said selected data based on said measure of similarity.

33. An apparatus according to claim 32 further comprising a computer module operative to perform a statistical hypothesis test on said selected data and said estimate thereof, to determine if there is a statistically significant deviation between them.

34. An apparatus according to claim 33 wherein said statistical hypothesis test is a sequential probability ratio test.

35. An interconnected system for monitoring a data source for determining all operating condition of a monitored system relative to a model system, comprising:

a monitored operational system selected from the group consisting of a biological system, a financial system, an industrial system, a chemical system and a physical system;

at least one first computer module operative to accumulate reference data characteristic of learned states of a reference operational condition of a model system of said group and to accumulate selected data characteristic of an operational condition of a selected system of said group;

a second computer module operative to perform a similarity angle analysis on said reference data and on said selected data for determining similarity angle data characteristic of a similarity value; and

a third computer program module operative to receive and operate on the similarity angle data to determine whether a deviation exists for the monitored operational system relative to the model system.

36. The interconnected system as defined in claim 35 wherein said reference operational condition of said model system is selected from the group consisting of a normal operational condition and a deviating operational condition.

37. The interconnected system as defined in claim 35 wherein said second computer module includes a computer program which performs a sequential probability ratio test on said similarity angle data for at least one of said reference data and said selected data.

38. The interconnected system as defined in claim 35 wherein said similarity angle analysis of said second module computer program comprises a bounded angle ratio test to determine a similarity angle characteristic of the operating condition of the monitored system relative to the operational condition of the model system.

39. The interconnected system as defined in claim 38 wherein the bounded angle ratio test includes a computer program to establish a reference point R positioned adjacent a similarity domain line characteristic of a similarity domain with the point R at a distance h of closest approach to said similarity domain line.

40. The interconnected system as defined in claim 39 wherein the second computer module establishes a minimum value X_min and a maximum value X_max over a statistical distribution over the similarity domain.

41. The interconnected system as defined in claim 40 wherein a line from the reference point R to said similarity domain intersects at point X_med, a median over all corresponding values in said reference data.

42. The interconnected system as defined in claim 41 wherein an angle defined by lines from the reference point R to the values X_min and X_max is 90°

.

43. The interconnected system as defined in claim 42 wherein the similarity angle is defined by:

θ

=arc tan(X₁/h)−

arc tan(X₀/h), where X₁ is a larger value and X₀ is a smaller value in a set formed by a first value from said selected data and a second corresponding value selected from said reference data.

44. The interconnected system as defined in claim 35 wherein the data source comprises at least two sources of data and said first computer module includes a computer program which operates to monitor at least two sources of data separately when the at least two sources of data are uncorrelated.

45. The interconnected system as defined in claim 35 wherein the data source comprises at least two sources of data and said first computer module includes a computer program which operates to monitor all the sources of data and perform a regression analysis on the similarity angle data.

46. The interconnected system as defined in claim 45 wherein the regression analysis comprises a sequential probability ratio test.

47. The interconnected system as defined in claim 35 wherein estimated data for the monitored system is provided from preaccumulated data source based upon determining a sensor of the data source has malfunctioned.

48. The interconnected system as defined in claim 47 wherein the data source derives from a plurality of individual sources of data which provide signals selected from the group of non-linearly and linearly related signals.

49. An apparatus for determining statistical similarity between a reference system and a selected system, comprising:

a data source for providing current data of a selected system;

a data source for providing reference data of a reference system; and

a computer module operative to render a measure of statistical similarity between the current data and the reference data, the computer module determining a statistical combination of a set of similarity values for corresponding data values of the current data and the reference data, wherein the similarity values are determined by a computer program which compares the data values from the current data to the corresponding data values from the reference data by performing a bounded angle ratio test.

50. The apparatus as defined in claim 49 wherein said computer module is further operative to conclude whether or not a deviated state exists for the selected system relative to the reference system.

51. The apparatus as defined in claim 49 wherein said first computer module is operative to compare:

a first angle in a first triangle having a base opposite said first angle with a length along the base proportional to the difference between said corresponding data values comprised of a value of said current data and a value of said reference data, to a second angle in a second triangle having a base opposite said second angle with a length proportional to a range over all said corresponding data values in said reference data.

52. The apparatus as defined in claim 49 comprising a computer module operative to carry out at least one of (a) generate an estimate of said selected data based on the measure of similarity and (b) generate an estimate of said selected data based on the measure of similarity and perform a statistical hypothesis test on said selected data and said estimate to determine any statistical deviation.