Process device diagnostics using process variable sensor signal

• US 6,601,005 B1
• Filed: 06/25/1999
• Issued: 07/29/2003
• Est. Priority Date: 11/07/1996
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Eryurek, Evren, Kavaklioglu, Kadir, Esboldt, Steven R.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Charioui, Mohamed
• Application Number:
  US09/344,631
• Time in Patent Office: 1,495 Days
• Field of Search: 702/45, 702/55, 702/69, 702/191, 702/195, 702/183, 702/104, 702/105, 738/612.3, 73/11.6, 738/613.55, 738/613.56, 738/613.57, 738/612.2, 738/611.2, 738/611.5, 340/606
• US Class Current: 702/104
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G05B 23/024 Quantitative history assessment, e.g. mathematical relationships between available data; Functions therefor; Principal component analysis [PCA]; Partial least square [PLS]; Statistical classifiers, e.g. Bayesian networks, linear regression or correlation analysis; Neural networks
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
• CPC Class Codes: G08C 19/02 in which the signal transmitted is magnitude of current or voltage G08C19/36, G08C19/38 take precedence

Abstract

Process device diagnostic is provided for diagnosing the condition of a process by receiving a process variable sensor signal. The process variable sensor senses vibration noise signals carried in a process fluid of the process. The vibration noise signals are generated by the process, such as by operation of process control elements. The diagnostics isolates the process noise signals in the process variable sensor signal and evaluates the isolated signal to diagnoses the process and the process devices.

Claims

1. A diagnostic device for use in a process control system, comprising:

a sensor signal input, the sensor signal related to a process variable of a process fluid of a process, the process variable sensed by a process variable sensor;

a signal preprocessor coupled to the sensor input having an isolated signal output comprising signal components in the sensor signal related to operation of the process;

a signal evaluator coupled to the isolated signal output having a condition output related to a condition of the process, the condition of the process different than the process variable; and

wherein the signal preprocessor isolates a frequency range and the signal evaluator compares an amplitude of the isolated frequency range to a threshold level.

2. The diagnostic device of claim 1 wherein the signal preprocessor comprises a wavelet preprocessor coupled to the sensor signal.

3. The diagnostic device of claim 2 wherein the wavelet processor performs wavelet transform.

4. The diagnostic device of claim 3 wherein the wavelet transform comprises a discrete wavelet transform.

5. The diagnostic device of claim 1 wherein the diagnostic device couples to a communication bus.

6. The diagnostic device of claim 5 wherein the communication bus comprises a two-wire loop.

7. The diagnostic device of claim 6 wherein the diagnostic device is fully powered with power received from the two-wire loop.

8. The diagnostic device of claim 1 wherein the sensor signal has a frequency response of at least 50 Hz.

9. A transmitter including the diagnostic device of claim 1.

10. The diagnostic device of claim 1 wherein the process variable sensor comprises a pressure sensor.

11. The diagnostic device of claim 1 wherein the process variable sensor comprises electrodes in a magnetic flowmeter.

12. The diagnostic device of claim 1 wherein the process variable sensor comprises a sensor in a vortex flowmeter.

13. The diagnostic device of claim 1 wherein the process variable sensor comprises a sensor in a coriolis flowmeter.

14. The diagnostic device of claim 1 wherein the sensor signal has a frequency of between 0 Hz and 200 Hz.

15. The diagnostic device of claim 1 wherein the signal preprocessor comprises a filter.

16. The diagnostic device of claim 1 wherein the condition relates to operation of a process control device.

17. The diagnostic device of claim 1 wherein the diagnostic device is implemented in a process monitor.

18. The diagnostic device of claim 1 wherein the diagnostic device is implemented in a control system.

19. The diagnostic device of claim 1 wherein the isolated signal output relates to a vibration noise signal carried in process fluid of the process.

20. The diagnostic device of claim 1 wherein the process variable sensor comprises a sensor in an ultrasonic flowmeter.

21. The diagnostic device of claim 1 wherein the condition of the process is related to condition of a process device selected from the group of devices consisting of valves, pumps, pump seals, discharge systems, actuators, solenoids, compressors, turbines, agitators, dampers, piping, fixtures and tanks.

22. A diagnostic method performed in a process control environment, the method comprising:

obtaining a process variable sensor signal;

isolating a process noise signal in the process variable sensor signal by isolating a frequency range; and

evaluating the isolated signal by comparing an amplitude of the isolated frequency range to a threshold level and providing a condition output related to the process, the condition different than the process variable.

23. The method of claim 22 wherein isolating comprises filtering the process variable sensor signal.

24. The method of claim 22 wherein isolating comprises performing a wavelet transformation on the process variable sensor signal.

25. The method of claim 22 wherein performing a wavelet transform comprises performing a discrete wavelet transform.

26. The method of claim 22 wherein evaluating comprises applying the isolated signal to a neural network.

27. The method of claim 22 wherein the process variable sensor signal comprises a pressure sensor signal.

28. The method of claim 22 wherein the process variable sensor signal comprises a sensor output from a coriolis flowmeter.

29. The method of claim 22 wherein the process variable sensor signal comprises a sensor output from a vortex flowmeter.

30. The method of claim 22 wherein the process variable sensor signal comprises electrode outputs from a magnetic flowmeter.

31. The method of claim 22 wherein the process variable sensor signal has a bandwidth of at least 50 Hz.

32. The method of claim 22 wherein the condition output relates to a condition of a process control device.

33. The method of claim 22 including fully powering the diagnostic device with power from a two-wire loop.

34. A process transmitter implementing the method of claim 22.

35. A process control system implementing the method of claim 22.

36. A process control device implementing the method of claim 22.

37. A process monitor implementing the method of claim 22.

38. A computer-readable medium having stored thereon instructions executable by a microprocessor system in a diagnostic device to diagnose condition of a process, the instructions comprising:

obtaining a process variable sensor signal;

isolating a process noise signal in the process variable sensor signal by isolating a frequency range;

evaluating the isolated signal by comparing an amplitude of the isolated frequency range to a threshold level, the condition different than the process variable; and

outputting the process condition in response to the evaluation.

39. A diagnostic device for use in a process control system, comprising:

a sensor signal input, the sensor signal related to a process variable of a process fluid of a process, the process variable sensed by a process variable sensor;

signal preprocessing means for isolating signal components in the sensor signal related to operation of the process and providing an isolated signal output;

signal evaluating means for diagnosing a condition of the process, the condition of the process different than the process variable; and

wherein the signal preprocessor isolates a frequency range and the signal evaluator compares an amplitude of the isolated frequency range to a threshold level.