System for monitoring an industrial process and determining sensor status
First Claim
1. A method of testing at least one of an industrial process and at least a first and second sensor for determining fault conditions therein, comprising the steps of:
- operating the at least first and second sensor to redundantly detect at least one physical variable of the industrial process to provide a first signal from said first sensor and a second signal from said second sensor, each said signal being characteristic of the one physical variable;
obtaining a difference function characteristic of the arithmetic difference pairwise between said first signal and said second signal at each of a plurality of different times of sensing the one physical variable;
obtaining a frequency domain transformation of said first difference function to procure Fourier coefficients corresponding to Fourier frequencies;
generating a composite function over time domain using the Fourier coefficients;
obtaining a residual function over time by determining the arithmetic difference between the difference function and the composite function, the residual function having reduced serially correlated noise;
operating on the residual function using computer means for performing a statistical analysis technique to determine whether an alarm condition is present in at least one of the industrial process and the at least first and second sensor, the residual function including white noise characteristics of an uncorrelated function of reduced skewness relative to the difference function and being input to the statistical analysis technique; and
said at least first and second sensor providing alarm information to an operator of the industrial process allowing modification of at least one of the industrial process and said at least first and second sensor when an alarm condition is detected.
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Accused Products
Abstract
A method and system for monitoring an industrial process and a sensor. The method and system include generating a first and second signal characteristic of an industrial process variable. One of the signals can be an artificial signal generated by an auto regressive moving average technique. After obtaining two signals associated with one physical variable, a difference function is obtained by determining the arithmetic difference between the two pairs of signals over time. A frequency domain transformation is made of the difference function to obtain Fourier modes describing a composite function. A residual function is obtained by subtracting the composite function from the difference function and the residual function (free of nonwhite noise) is analyzed by a statistical probability ratio test.
128 Citations
22 Claims
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1. A method of testing at least one of an industrial process and at least a first and second sensor for determining fault conditions therein, comprising the steps of:
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operating the at least first and second sensor to redundantly detect at least one physical variable of the industrial process to provide a first signal from said first sensor and a second signal from said second sensor, each said signal being characteristic of the one physical variable; obtaining a difference function characteristic of the arithmetic difference pairwise between said first signal and said second signal at each of a plurality of different times of sensing the one physical variable; obtaining a frequency domain transformation of said first difference function to procure Fourier coefficients corresponding to Fourier frequencies; generating a composite function over time domain using the Fourier coefficients; obtaining a residual function over time by determining the arithmetic difference between the difference function and the composite function, the residual function having reduced serially correlated noise; operating on the residual function using computer means for performing a statistical analysis technique to determine whether an alarm condition is present in at least one of the industrial process and the at least first and second sensor, the residual function including white noise characteristics of an uncorrelated function of reduced skewness relative to the difference function and being input to the statistical analysis technique; and said at least first and second sensor providing alarm information to an operator of the industrial process allowing modification of at least one of the industrial process and said at least first and second sensor when an alarm condition is detected. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of testing at least one of an industrial process and a sensor for determining fault conditions therein, comprising the steps of:
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operating at least one sensor to detect at least one physical variable of the industrial process to provide a real signal from said one sensor; generating an artificial signal characteristic of the one physical variable; obtaining a difference function characteristic of the difference pairwise between said real signal and said artificial signal at each of a plurality of different times of sensing the one physical variable; obtaining a frequency domain transformation of said difference function; generating a composite function over a time domain; obtaining a residual function over time by determining the difference between the difference function and the composite function; operating on the residual function using a computer means for performing a statistical analysis technique to determine whether an alarm condition is present in at least one of the industrial process and the at lest one sensor, the residual function including white noise characteristics of an uncorrelated signal of reduced skewness relative to the difference function and being input to the statistical analysis technique; and said at least one sensor providing alarm information to an operator of the industrial process allowing modification of at least one of the industrial process and the at least one sensor when an alarm condition is detected. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A system for testing at least one of an industrial process and a sensor for determining a fault condition therein, comprising:
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at least a first sensor to detect at least one physical variable of the industrial process to provide a real signal from said first sensor; first means for generating a second signal for comparison with said real signal from said first sensor; second means for determining a difference function characteristic of the arithmetic difference pairwise between said real signal and said second signal at each of a plurality of different times of sensing the one physical variable; third means for obtaining a residual function over time by means for determining the arithmetic difference between the difference function and the composite function, the residual function including white noise characteristics of an uncorrelated signal of reduced skewness; fourth means for operating on the residual function including a computer means for performing a statistical analysis technique and for determining whether an alarm condition is present in at least one of the industrial process and the at least first sensor and with said second means, said third means, and said fourth means cooperatively providing a function comprised of said white noise characteristics of uncorrelated signal of reduced skewness relative to the difference function as an input to the statistical analysis technique; and means for providing information allowing modification of at least one of the industrial process and the at least first sensor when an alarm condition is detected. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method of testing at least one of an industrial process and at least a first and second sensor for determining fault conditions therein, comprising the steps of:
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operating the at least first and second sensor to redundantly detect at least one physical variable of the industrial process to provide a first signal from said first sensor and a second signal from said second sensor, each said signal being characteristic of the one physical variable; obtaining a difference function characteristic of the arithmetic difference pairwise between said first signal and said second signal at each of a plurality of different times of sensing the one physical variable; obtaining a frequency domain transformation of said first difference function to procure Fourier coefficients corresponding to Fourier frequencies; generating a composite function over time domain using the Fourier coefficients; obtaining a residual function over time by determining the arithmetic difference between the difference function and the composite function, the residual function including white noise characteristics of an uncorrelated function of reduced skewness relative to the difference function; operating on the residual function using computer means for performing a statistical analysis technique to determine whether an alarm condition is present in at least one of the industrial process and the at least first and second sensor; and said at least a first and second sensor providing alarm information to an operator of the industrial process allowing modification of at least one of the industrial process and the at least first and second sensor when an alarm condition is detected.
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22. A method of testing at least one of an industrial process and at least one sensor for determining fault conditions therein, comprising the steps of:
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operating the at least one sensor to detect at least one physical variable of the industrial process to provide a real signal from said at least one sensor; generating an artificial signal characteristic of the one physical variable; obtaining a difference function characteristic of the difference pairwise between said real signal and said artificial signal at each of a plurality of different times of sensing the one physical variable; obtaining a frequency domain transformation of said difference function; generating a composite function over a time domain; obtaining a residual function over time by determining the difference between the difference function and the composite function, the residual function comprising white noise characteristics of an uncorrelated signal of reduced skewness relative to the difference function; operating on the residual function using a computer means for performing a statistical analysis technique to determine whether an alarm condition is present in at least one of the industrial process and the at least one sensor; and said at least one sensor providing alarm information to an operator of the industrial process allowing modification of at least one of the industrial process and the at least one sensor when an alarm condition is detected.
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Specification