METHODS AND SYSTEMS FOR FAULT DIAGNOSIS IN OBSERVATION RICH SYSTEMS

• US 20100241251A1
• Filed: 03/23/2009
• Published: 09/23/2010
• Est. Priority Date: 03/23/2009
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Kuhn, Lukas D., de Kleer, Johan
• Granted Patent: US 8,359,110 B2
• Time in Patent Office: Days
• US Class Current: 700/31
• CPC Class Codes: G05B 23/0245 based on a qualitative model, e.g. rule based; if-then decisions
• CPC Class Codes: G05B 23/0262 Confirmation of fault detection, e.g. extra checks to confirm that a failure has indeed occurred
• CPC Class Codes: Y02P 90/80 Management or planning

Abstract

Diagnostic systems and methods are presented for determining the current condition of a production plant and the resources thereof, in which successively more complex diagnostic abstractions are used to determine the plant condition, with a more complex abstraction being selected when the most recently selected diagnostic abstraction is logically inconsistent with the current fault status indications.

Claims

1. A control system for controlling operation of a production system with a plant that can achieve one or more production goals, the control system comprising:

a planner operative to provide plans for execution using one or more plant resources in the plant;

a model of the plant; and

a diagnosis system comprising;

a plurality of diagnostic abstractions individually representing one or more fault assumptions regarding resources of the plant with a complexity of the fault assumption or assumptions of each diagnostic abstraction being different,

a belief model comprising at least one fault status indication for at least one resource of the plant, and

a diagnoser including;

an abstraction diagnosis component operative to initially select a first one of the plurality of diagnostic abstractions having the least complex fault assumption or assumptions and to subsequently select another one of the diagnostic abstractions having more complex fault assumptions when a most recently selected diagnostic abstraction is logically inconsistent with the current fault status indications in the belief model, and

a domain diagnosis component operative to determine a current plant condition and to update the belief model based at least partially on the currently selected diagnostic abstraction, a previously executed plan, at least one corresponding observation from the plant, and the plant model.

2. The control system of claim 1, wherein the plurality of diagnostic abstractions includes at least one abstraction representing a single fault assumption and at least one abstraction representing a multiple fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

3. The control system of claim 2, wherein the plurality of diagnostic abstractions includes at least one abstraction representing a persistent fault assumption and at least one abstraction representing an intermittent fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

4. The control system of claim 3, wherein the plurality of diagnostic abstractions includes at least one abstraction representing an interaction fault assumption and at least one abstraction representing a non-interaction fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

5. The control system of claim 2, wherein the plurality of diagnostic abstractions includes at least one abstraction representing an interaction fault assumption and at least one abstraction representing a non-interaction fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

6. The control system of claim 1, wherein the plurality of diagnostic abstractions includes at least one abstraction representing a persistent fault assumption and at least one abstraction representing an intermittent fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

7. The control system of claim 6, wherein the plurality of diagnostic abstractions includes at least one abstraction representing an interaction fault assumption and at least one abstraction representing a non-interaction fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

8. The control system of claim 1, wherein the plurality of diagnostic abstractions includes at least one abstraction representing an interaction fault assumption and at least one abstraction representing a non-interaction fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

9. The control system of claim 8, wherein the domain diagnosis component is operative to identify at least one interaction fault involving interaction of two or more resources of the plant.

10. The control system of claim 1, wherein the belief model comprises:

a list of good or exonerated resources of the plant;

a list of bad or suspected resources of the plant; and

a list of unknown resources of the plant.

11. The control system of claim 10, wherein at least one fault status indication in the belief model indicates a fault probability for at least one resource of the plant.

12. The control system of claim 1, wherein at least one fault status indication in the belief model indicates a fault probability for at least one resource of the plant.

13. A method of determining a current condition of re sources of a production plant, the method comprising:

selecting a first one of a plurality of diagnostic abstractions having the least complex fault assumption or assumptions regarding resources of the plant;

determining a current plant condition based at least partially on the currently selected diagnostic abstraction, a previously executed plan, at least one corresponding observation from the plant, and a plant model; and

selectively selecting another one of the diagnostic abstractions having more complex fault assumptions when a most recently selected diagnostic abstraction is logically inconsistent with the current fault status indications.

14. The method of claim 13, further comprising:

maintaining a belief model comprising at least one fault status indication for at least one resource of the plant; and

updating the belief model based at least partially on the currently selected diagnostic abstraction, a previously executed plan, at least one corresponding observation from the plant, and the plant model.

15. The method of claim 13, wherein the plurality of diagnostic abstractions includes at least one abstraction representing a single fault assumption and at least one abstraction representing a multiple fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

16. The method of claim 13, wherein the plurality of diagnostic abstractions includes at least one abstraction representing a persistent fault assumption and at least one abstraction representing an intermittent fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

17. The method of claim 13, wherein the plurality of diagnostic abstractions includes at least one abstraction representing an interaction fault assumption and at least one abstraction representing a non-interaction fault assumption regarding resources of the plant with successively more complex fault assumptions, respectively.

18. The method of claim 17, wherein determining a current plant condition comprises identifying at least one interaction fault involving interaction of two or more resources of the plant.

19. A computer readable medium having computer executable instructions for performing the steps of:

selecting a first one of a plurality of diagnostic abstractions having the least complex fault assumption or assumptions regarding resources of a production plant;

determining a current plant condition based at least partially on the currently selected diagnostic abstraction, a previously executed plan, at least one corresponding observation from the plant, and a plant model; and

selectively selecting another one of the diagnostic abstractions having more complex fault assumptions when a most recently selected diagnostic abstraction is logically inconsistent with the current fault status indications.

20. The computer readable medium of claim 19, comprising further computer executable instructions for:

maintaining a belief model comprising at least one fault status indication for at least one resource of the plant; and

updating the belief model based at least partially on the currently selected diagnostic abstraction, a previously executed plan, at least one corresponding observation from the plant, and the plant model.