Methods and Apparatuses For Monitoring A System

• US 20090326784A1
• Filed: 03/27/2007
• Published: 12/31/2009
• Est. Priority Date: 07/27/2006
• Status: Abandoned Application

• Current Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Inventors: Mills, Andrew, Tanner, Graham Francis
• Application Number:
  US12/308,952
• Publication Number:
  US 20090326784A1
• Time in Patent Office: Days
• US Class Current: 701/100
• CPC Class Codes: G05B 2219/2623 Combustion motor
• CPC Class Codes: G05B 2219/32408 Case based diagnosis to assist decision maker, operator
• CPC Class Codes: G05B 23/0278 Qualitative, e.g. if-then rules; Fuzzy logic; Lookup tables; Symptomatic search; FMEA
• CPC Class Codes: Y04S 10/52 Outage or fault management, e.g. fault detection or location

Abstract

A method for determining probable fail cases of a system includes the steps of:

• • (a) receiving a pattern of input features, each feature representing measurable indicators which themselves are indicative of the condition of the system;
  • (b) providing a set of fail cases, each fail case being represented by an expected pattern of input features, and each fail case being associated with a rule in reverse polish notation which produces a true result if the expected pattern for that rule correlates with a pattern of input features or a false result if the expected pattern for that rule does not correlate with a pattern of input features; and
  • (c) applying the received pattern of input features to each rule to determine whether the received pattern has a true result or a false result for the respective fail case, a true result denoting a probable fail case of the system.

Typically, the system is a complex mechanical system such as a power plant, including for example gas turbine, spark ignition and compression ignition internal combustion engines.

Claims

1-19. -19. (canceled)

20. A method for determining probable fail cases of a system, the method including the steps of:

(a) receiving a pattern of input features, each feature representing measurable indicators which themselves are indicative of the condition of the system;

(b) providing a set of fail cases, each fail case being represented by an expected pattern of input features, the expected pattern specifying a set of features which are expected to be present in the fail case and a set of features which are expected to be absent in the fail case; and

(c) for each fail case, performing a comparison of the expected pattern of input features representing that fail case to determine probable fail cases of the system.

21. A method according to claim 20, wherein each fail case is associated with a rule in reverse polish notation which produces a true result if the expected pattern for that rule correlates with a pattern of input features or a false result if the expected pattern for that rule does not correlate with a pattern of input features, and in step (c) the comparison is performed by applying the received pattern of input features to each rule to determine whether the received pattern has a true result or a false result for the respective fail case, a true result denoting a probable fail case of the system.

22. A method according to claim 21, wherein the rules are stored in an updatable look-up table.

23. A method according to claim 20, wherein each fail case is associated with one or more weighting factors, each weighting factor representing a likelihood of a fault being present in a respective system component, the method further including the steps of:

(d) for each probable fail case from step (c), calculating a score for a comparison of the expected pattern

of input features representing that fail case with the received pattern of input features; and

(e) combining, for each fail case, the score calculated at step (d) with the or each weighting factor associated with that fail case in order to determine a probable faulty system component.

24. A method according to claim 23, wherein each system component is a line replaceable unit.

25. A method according to claim 23, wherein the weighting factors are stored in an updatable look-up table.

26. A method according to claim 20, wherein in step (c) the comparison is performed by the sub-steps of:

(c-i) for each fail case, calculating a score for a comparison of the expected pattern of input features representing that fail case with the received pattern of input features;

(c-ii) determining a subset of probable fail cases based on the scores calculated at step (c-i);

(c-iii) for each fail case of the subset, generating a further input feature by;

predicting, from a model of the system, a value for a further measurable indicator,

receiving a measured value for the further indicator, and

comparing the predicted and received values;

(c-iv) for each fail case of the subset, calculating a score for a comparison of the expected pattern of input features representing that fail case with the received pattern of input features and the further input feature generated at step (c-iii); and

(c-v) determining most probable fail cases based on the scores calculated at step (c-iv).

27. A method according to claim 26, wherein each fail case is associated with one or more weighting factors, each weighting factor representing a likelihood of a fault being present in a respective system component, the method further including the step of:

(d) combining, for each most probable fail case from sub-step (c-v), the score calculated at sub-step (c-iv) with the or each weighting factor associated with that fail case in order to determine a probable faulty system component.

28. A method according to claim 27, wherein each system component is a line replaceable unit.

29. A method according to claim 27, wherein the weighting factors are stored in an updatable look-up table.

30. A method according to claim 20, further including preliminary steps of measuring the indicators and forming the pattern of input features.

31. A method according to claim 20, wherein the system is a gas turbine engine.

32. A method according to claim 31, wherein the gas turbine engine is mounted on an aircraft.

34. A computer system configured to perform the method of claim 20.

35. A computer program which, when run on a suitable computer system, performs the method of claim 20.

36. A computer program product carrying the computer program of claim 34.