Prediction of error magnitude in a pressure transmitter

• US 6,701,274 B1
• Filed: 08/27/1999
• Issued: 03/02/2004
• Est. Priority Date: 08/27/1999
• Status: Expired due to Term

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Lenz, Gary A., Eryurek, Evren, Kavaklioglu, Kadir
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): VO, HIEN XUAN
• Application Number:
  US09/384,876
• Time in Patent Office: 1,649 Days
• Field of Search: 702/140, 702/133, 702/182, 702/183, 702/130, 702/99, 702/138, 702/98, 700/79, 700/54, 700/28, 700/32, 700/33
• US Class Current: 702/140
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: G01D 3/022 having an ideal characteristic, map or correction data stored in a digital memory
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect

Abstract

A pressure transmitter with an output predicting the magnitude of error in the pressure transmitter'"'"'s output. A pressure sensor is adapted to sense a process pressure. A controller coupled to the pressure sensor generates a transmitter output representing the process pressure. A memory stores predetermined data predicting magnitudes of transmitter output error as a function of cumulative excessive sensor output levels, and also stores a record of cumulative excessive sensor output levels. The controller calculates a predicted present magnitude of transmitter output error as a function of the accumulated record and the predetermined data, and generates the prediction output.

Claims

1. A pressure transmitter, comprising:

a pressure sensor adapted to sense a process pressure;

a controller coupled to the pressure sensor and generating a transmitter output representing the process pressure;

memory storing predetermined data predicting magnitudes of transmitter output error as a function of cumulative excessive sensor output levels, and storing a record of cumulative excessive sensor output levels; and

the controller calculating a predicted present magnitude of transmitter output error as a function of the accumulated record and the predetermined data, and generating a prediction output.

2. The pressure transmitter of claim 1 wherein the record is representative of physical changes to the sensor resulting from overpressure.

3. The pressure transmitter of claim 1 wherein the prediction output represents a calibration shift.

4. The pressure transmitter of claim 1 wherein the prediction output is independent of thie present process pressure.

5. The pressure transmitter of claim 1 wherein the prediction output is a function of present process pressure.

6. The pressure transmitter of claim 1 wherein the prediction output includes both a sensor offset error independent of present process pressure and a sensor gain error proportional to present process pressure.

7. The pressure transmitter of claim 1 wherein the predetermined data is based on a computer model of overpressure damage to a comparable sensor.

8. The pressure transmitter of claim 1 wherein the predetermined data is based on experimental testing of overpressure damage to a comparable sensor.

9. The pressure transmitter of claim 1 further comprising a temperature sensor coupled to the controller, the predetermined data predicting magnitudes of transmitter output error as a function of cumulative excessive temperature levels, and the predicted magnitude of transmitter output error being further a function of cumulative excess temperature levels.

10. The pressure transmitter of claim 9 further comprising a humidity sensor coupled to the controller, the predicted magnitude of transmitter output error being further a function of humidity.

11. The pressure transmitter of claim 1 wherein the record is a function of the magnitudes and durations of excessive sensor output levels.

12. The pressure transmitter of claim 1 wherein the controller further stores predetermined data predicting the residual useful life of the pressure sensor in memory.

13. The pressure transmitter of claim 1, wherein the predicted present magnitude of transmitter output error is calculated by the controller using fuzzy logic.

14. The pressure transmitter of claim 1 wherein the predicted present magnitude of transmitter output error is calculated using neural networks.

15. The pressure transmitter of claim 1 wherein the predicted present magnitude of transmitter output error is calculated by the controller using wavelet analysis.

16. The pressure transmitter of claim 1 wherein the predicted present magnitude of transmitter output error is calculated by the controller using autoregression.

17. The pressure transmitter of claim 1 wherein the predicted present magnitude of transmitter output error is calculated by the controller using recursive filtering.

18. The pressure transmitter of claim 1 wherein the predicted present magnitude of transmitter output error is calculated by the controller using adaptive self tuning.

19. The pressure transmitter of claim 1 wherein the transmitter output is corrected as a function of the prediction output.

20. The pressure transmitter of claim 1 wherein the transmitter output comprises an estimated process variable during an occurrence of an excessive sensor output.

21. The pressure transmitter of claim 20 wherein the process variable is estimated by a neural network.

22. The pressure transmitter of claim 20 wherein the process variable is estimated by fuzzy logic.

23. The pressure transmitter of claim 20 wherein the process variable is estimated by curve fitting.

24. The pressure transmitter of claim 20 wherein the process variable is estimated by regression algorithm.

25. A method of predicting the present magnitude of transmitter output error in a pressure transmitter receiving an applied process pressure and having an embedded controller, comprising:

accessing sensed process pressure from a pressure sensor;

generating a transmitter output with a magnitude representing the process pressure;

accessing predetermined data stored in a memory, the data predicting magnitudes of transmitter output error as a function of cumulative excess process pressures;

storing a record of cumulative excess process pressures in the memory, and

generating a prediction output in the controller predicting a present magnitude of transmitter output error as a function of the stored record and the accessed data.

26. The method of claim 25 including correcting the transmitter output as a function of prediction output.

27. The method of claim 25 wherein generating a prediction output includes applying fuzzy logic to the sensed process pressure.

28. The method of claim 25 wherein generating a prediction output includes applying the sensed process pressure to a neural network.

29. The method of claim 25 wherein generating a prediction output includes applying the sensed process pressure to a rule.

30. The method of claim 29 wherein the rule comprises comparison to a threshold.

31. The method of claim 25 wherein the prediction output is related to expected lifetime of the pressure sensor.

32. The method of claim 25 including estimating process pressure during occurrence of an excess process pressure.

33. The method of claim 32 wherein the process variable is estimated by a neural network.

34. The method of claim 32 wherein the process variable is estimated by fuzzy logic.

35. The method of claim 32 wherein the process variable is estimated by curve fitting.

36. The method of claim 32 wherein the process variable is estimated by regression algorithm.

37. A pressure transmitter, comprising:

means for sensing a process pressure and for generating a sensor output;

means, coupled to the sensor output, for generating a transmitter output representing the process pressure;

means, coupled to the sensor output, for storing a predetermined record predicting magnitudes of transmitter output error as a function of cumulative excessive sensor output levels, and for storing a record of cumulative excessive sensor output levels; and

for generating a prediction output predicting a present magnitude of transmitter output error.

38. A computer readable medium having stored thereon instructions executable by an embedded controller in a pressure transmitter to cause the pressure transmitter to generate a predictive output predicting transmitter error caused by excessive process pressure, the instructions comprising:

accessing sensed process pressure from a pressure sensor;

generating a transmitter output with a magnitude representing the process pressure;

accessing predetermined data stored in a memory, the data predicting magnitudes of transmitter output error as a function of cumulative excess process pressures;

storing a record of cumulative excess process pressures in the memory, and

generating a prediction output in the controller predicting a present magnitude of transmitter output error as a function of the stored record and the accessed data.