Device in a process system for detecting events

• US 6,397,114 B1
• Filed: 05/03/1999
• Issued: 05/28/2002
• Est. Priority Date: 03/28/1996
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Warrior, Jogesh, Eryurek, Evren
• Primary Examiner(s): Grant, William
• Assistant Examiner(s): Rao, Sheela S.
• Application Number:
  US09/303,869
• Time in Patent Office: 1,121 Days
• Field of Search: 700/48-50,51 702/183,33,59 706/2-8 714/735
• US Class Current: 700/51
• CPC Class Codes: G05B 13/0275 using fuzzy logic only
• CPC Class Codes: G05B 21/02 electric
• CPC Class Codes: G05B 23/0221 Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods
• CPC Class Codes: G05B 23/0278 Qualitative, e.g. if-then rules; Fuzzy logic; Lookup tables; Symptomatic search; FMEA

Abstract

A process device couples to a process control loop. The process device receives process signals. A memory in the process device contains a nominal parameter value and a rule. Computing circuitry calculates a statistical parameter of the process signal and operates on the statistical parameter and the stored nominal value based upon the stored rule and responsively provides an event output based upon the operation. Output circuitry provides an output in response to the event output

Claims

1. A process device coupled to a process control loop configured to control a process fluid, comprising:

a process variable input to receive a process variable of the process control loop, the process variable related to the process;

a process event input to receive a process event generated by a process device on the process control loop related to an occurrence of an event in the process, the process event selected from the group of process events consisting of drift, bias, noise, stuck and spike;

a control signal input to receive a control signal and to control the process fluid; and

an inference engine coupled to the process variable input the control signal input and the process event input, the inference engine having a faulty element output which is a function of the process variable, the control signal and the process event, the faulty element output identifies a faulty component in the process which caused the process event.

2. The process device of claim 1 wherein the inference engine includes stored process data.

3. The process device of claim 2 wherein the process data comprises process history information.

4. The process device of claim 2 wherein the process data comprises logged process variables.

5. The process device of claim 1 wherein the process event is detected with a rule.

6. The process device of claim 1 wherein the process event is detected with a rule, a nominal parameter value and a statistical parameter.

7. The process device of claim 6 wherein the nominal parameter value comprises a trained value and a sensitivity parameter.

8. The process device of claim 6 wherein the statistical parameter is selected from the group consisting of standard deviation, mean, sample variance, root-mean-square (RMS), range, and rate of change.

9. The process device of claim 1 wherein the process control loop is selected from the group consisting of two wire process control loops, three wire process control loops and four wire process control loops.

10. The process device of claim 9 wherein the device is completely powered with power received from the process control loop.

11. The process device of claim 1 wherein the inference engine includes computation circuitry operating in accordance with a rule.

12. The process device of claim 11 wherein the faulty element output is a function of a comparison of the control signal and the process variable.

13. The process device of claim 1 wherein the inference engine performs transmitter diagnostics in response to a process event.

14. The process device of claim 1 wherein the inference engine instructs a device on the process control loop to perform on-board diagnostics.

15. The process device of claim 1 wherein the faulty element output comprises a warning.

16. The process device of claim 1 wherein the faulty element output provides information to an operator.

17. The process device of claim 1 wherein the inference engine includes fuzzy logic.

18. The process device of claim 1 wherein the inference engine includes a neural network.

19. The process device of claim 1 wherein the inference engine examines the process event and identifies a specific event in the process control system.

20. The process device of claim 1 wherein the inference engine initiates a shutdown procedure to shut down the process in the process event.

21. The process device of claim 1 wherein the process device comprises a transmitter.

22. The process device of claim 1 wherein the process device comprises a controller.

23. The process device of claim 1 wherein the process device comprises a communicator.

24. The process device of claim 1 wherein the process device comprises a control room equipment.

25. The process device of claim 1 wherein the process device comprises a PC.

26. The process device of claim 1 wherein the inference engine examines a plurality of process variables in response to a process event.

27. The process device of claim 1 wherein the inference engine identifies a known device condition in response to a process event.

28. The process device of claim 1 wherein the inference engine identifies a faulty component in response to a process event.

29. The process device of claim 1 wherein the inference engine comprises an expert system.

30. The process device of claim 1 wherein the inference engine further provides a condition output which identifies a known process condition.

31. A method of diagnosing a process controlled by a process control loop configured to control a process fluid, comprising:

obtaining a process variable of the process control loop related to the operation of process;

obtaining a process event related to an event generated by a process device on the process control loop in the process, the process selected from the group of process events consisting of drift, bias, noise, stuck and spike;

obtaining a control signal used to control the process fluid; and

computing a faulty element output related to a faulty element in the process control system in response to the process variable, the process event, and the control signal, the faulty element being the cause of the process event.

32. The method of claim 31 wherein providing a faulty element output includes informing an operator.

33. The method of claim 31 wherein providing a faulty element output comprises comparing the process variable, process event and control signal to process data.

34. The method of claim 31 wherein the process data comprises process history information.

35. The method of claim 31 wherein the process data comprises logged process variables.

36. The method of claim 31 wherein the process event is detected with a rule.

37. The method of claim 36 including detecting the process event by applying a rule using a nominal parameter value and a statistical parameter.

38. The method of claim 37 wherein the nominal parameter value comprises a trained value and a sensitivity parameter.

39. The method of claim 31 wherein providing a faulty element output includes instructing a process device to perform on-board diagnostics.

40. The method of claim 31 including evaluating results of the diagnostics through on-board diagnostics residents in a process device.

41. The method of claim 31 wherein providing a faulty element output includes identifying a component.

42. The method of claim 31 wherein providing a faulty element output includes identifying a process condition.

43. The method of claim 31 wherein providing a faulty element output includes applying fuzzy logic to the process variable.

44. The method of claim 31 wherein providing a faulty element output includes applying the process variable to a neural network.

45. The method of claim 31 wherein providing a faulty element output includes applying a rule to the process variable.

46. A process device comprising a transmitter implementing the method of claim 31.

47. A process device comprising a controller implementing the method of claim 31.

48. A process device comprising a PC implementing the method of claim 31.

49. A process device comprising control room equipment implementing the method of claim 31.

50. The method of claim 31 including identifying a known process condition in response to the variable, process event and control signal.

51. A computer-readable medium having stored thereon instructions executable by a microprocessor system in a process device to identify a fault in a process control loop configured to control a process fluid, the instructions comprising:

obtaining a process variable of the process control loop related to operation of the process;

obtaining a process event generated by a process device on the process control looprelated to an event in the process, the process selected from the group of process events consisting of drift, bias, noise, stuck and spike;

obtaining a control signal used to control the process fluid; and

computing a faulty element output related to a faulty element in the process control system in response to the process variable, the process event, and the control signal element in the process in response to the process variable, the process event, and the control signal, the faulty element being the cause of the process event.

52. A process device coupled to a process control loop used to control a process fluid, comprising:

a process variable input means for receiving a process variable of the process related to operation of the process;

a process event input means for receiving a process event of the process controlled by the process control loop generated by a process device on the process control loop, the process selected from the group of process events consisting of drift, bias, noise, stuck and spike;

a control signal input means for requiring a control signal used to control the process fluid; and

inference engine means for providing a faulty element output as a function of the process variable control signal and the process event, the faulty element output identifying a faulty component in the process control system, the faulty element being the cause of the process event.