System for monitoring non-coincident, nonstationary process signals

• US 6,839,655 B2
• Filed: 05/25/2001
• Issued: 01/04/2005
• Est. Priority Date: 05/25/2001
• Status: Expired due to Fees

• Current Assignee: U Chicago Argonne, LLC
• Original Assignee: University of Chicago
• Inventors: Wegerich, Stephan W., Gross, Kenneth C.
• Primary Examiner(s): NGHIEM, MICHAEL P
• Application Number:
  US09/865,953
• Publication Number:
  US 20030028349A1
• Time in Patent Office: 1,320 Days
• Field of Search: 702/71, 702/179, 702/182, 702/183, 702/185, 702/190, 702/191, 700/29, 700/30, 714/736, 340/146.2, 340/500
• US Class Current: 702/179
• CPC Class Codes: G05B 19/41805 characterised by assembly
• CPC Class Codes: G05B 2219/40554 Object recognition to track object on conveyor
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

An improved system for monitoring non-coincident, non-stationary, process signals. The mean, variance, and length of a reference signal is defined by an automated system, followed by the identification of the leading and falling edges of a monitored signal and the length of the monitored signal. The monitored signal is compared to the reference signal, and the monitored signal is resampled in accordance with the reference signal. The reference signal is then correlated with the resampled monitored signal such that the reference signal and the resampled monitored signal are coincident in time with each other. The resampled monitored signal is then compared to the reference signal to determine whether the resampled monitored signal is within a set of predesignated operating conditions.

Claims

1. A method for monitoring the operating condition of a system characterized by a succession of waveforms, comprising the steps of:

obtaining a reference waveform having a reference sample count;

obtaining a monitored waveform from the system;

resampling the monitored waveform with a digital fractional resampling filter such that the sample count of the monitored waveform matches the reference sample count of the reference waveform; and

comparing the resampled monitored waveform to the reference waveform to determine the operating condition of the system, wherein the comparing step comprises;

obtaining variance information for each sample in the reference waveform;

differencing the reference waveform and the resampled monitored waveform to produce a residual waveform; and

performing a sequential probability ratio test on a sequence of samples in said residual waveform using the variance information.

2. The method of claim 1, wherein the comparing step comprises a pair-wise comparison of like sample values from each of the resampled monitored waveform and the reference waveform.

3. The method of claim 1, wherein the comparing step comprises comparing the resampled monitored waveform to the reference waveform using a sequential probability ratio test.

4. The method of claim 1, further comprising the step of aligning the resampled monitored waveform with the reference waveform.

5. The method of claim 1, wherein the system comprises an industrial device.

6. A method for monitoring the operating condition of a system characterized by a succession of waveforms, comprising the steps of:

obtaining a reference waveform having a reference sample count;

obtaining a monitored waveform from the system;

resampling the monitored waveform with a digital fractional resampling filter such that the sample count of the monitored waveform matches the reference sample count of the reference waveform;

aligning the resampled monitored waveform with the reference waveform; and

comparing the resampled monitored waveform to the reference waveform to determine the operating condition of the system,

wherein the aligning step includes the use of a bounded angle ratio test.

7. A method for monitoring the operating condition of a system characterized by a succession of waveforms, comprising the steps of:

obtaining a reference waveform having a reference sample count;

obtaining a monitored waveform from the system;

resampling the monitored waveform with a digital fractional resampling filter such that the sample count of the monitored waveform matches the reference sample count of the reference waveform; and

comparing the resampled monitored waveform to the reference waveform to determine the operating condition of the system,

wherein the system comprises a biological heart.

8. A method for monitoring the operating condition of a system characterized by a succession of signals, comprising the steps of:

using an automated system to define a reference signal having a reference sample count;

using an automated system to obtain a monitored signal from the system;

using an automated system to resample the monitored signal with a digital fractional resampling filter such that the sample count of the monitored signal matches the reference sample count of the reference signal; and

using an automated system to compare the resampled monitored signal to the reference signal to determine the operating condition of the system,

wherein the comparing step comprises using an automated system to compare the resampled monitored signal to the reference signal using a sequential probability ratio test, and wherein the comparing step further comprises;

determining variance information for each sample in said reference signal;

using an automated system to difference the reference signal and the resampled monitored signal to produce a residual signal; and

performing a sequential probability ratio test on a sequence of samples in the residual signal using the variance information.

9. A computer system for monitoring the operating condition of a system characterized by a succession of waveforms, comprising:

computer readable program code means for storing and retrieving a reference waveform having a reference sample count;

computer readable program code means for receiving a monitored waveform from the system;

computer readable program code means for resampling the monitored waveform with a digital fractional resampling filter so that its sample count matches the reference sample count of the reference waveform; and

computer readable program code means for comparing the resampled monitored waveform to the reference waveform to determine the operating condition of the system,

wherein the comparing means compares the resampled monitored waveform to the reference waveform using a sequential probability ratio test, and wherein the comparing means receives variance information for each sample in said reference waveform, differences the reference waveform and the resampled monitored waveform to produce a residual waveform, and performs a sequential probability ratio test on a sequence of samples in said residual waveform using the variance information.

10. The computer program product according to claim 9, further comprising computer readable program code means for aligning the resampled monitored waveform with the reference waveform.

11. A computer system for monitoring the operating condition of a system characterized by a succession of waveforms, comprising:

computer readable program code means for storing and retrieving a reference waveform having a reference sample count;

computer readable program code means for receiving a monitored waveform from the system;

computer readable program code means for resampling the monitored waveform with a digital fractional resampling filter so that its sample count matches the reference sample count of the reference waveform;

computer readable program code means for aligning the resampled monitored waveform with the reference waveform; and

computer readable program code means for comparing the resampled monitored waveform to the reference waveform to determine the operating condition of the system,

wherein the aligning means uses a bounded angle ration test.

12. The computer program product according to claim 11, wherein the comparing means performs a pair-wise comparison of like sample values from each of the resampled monitored waveform and the reference waveform.

13. The computer program product according to claim 11, wherein the comparing means compares the resampled monitored waveform to the reference waveform using a sequential probability ratio test.

14. The computer program product according to claim 11, wherein the system comprises a biological system.

15. The computer program product according to claim 11, wherein the system comprises an industrial device.