Method and apparatus for detecting and identifying faulty sensors in a process
AssigneeFisher-Rosemount Systems, Inc.
InventorsS. Joe Qin, Ricardo H. Dunia, Randall L. Hayes
Life of this patent
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Abstract
A method and apparatus is provided for detecting a faulty sensor within a process control system having a set of sensors, each of which produces an associated sensor output signal. The method and apparatus produce a set of sensor estimate signals from the sensor output signals using principal component analysis and then determine a validity index for each of the sensors as a ratio of two residuals, wherein each of the residuals represents a different measure of the difference between the sensor output signals and the sensor estimate signals. The determined validity indexes are then used to detect a failure of one of the sensors and/or to identify which one of the sensors has failed.
Claims40
A method of detecting a faulty sensor within a process control system having a set of sensors each of which produces an associated sensor output signal, the method comprising the steps of:
- producing a set of sensor estimate signals from a combination of a plurality of the sensor output signals wherein each sensor estimate signal comprises an estimate of the output of a different one of the sensors;
- determining a validity index for one of the set of sensors as a function of a residual indicative of a measure of the difference between the sensor estimate signals and the sensor output signals;
- and
- using the validity index associated with the one of the sensors to ascertain if the one of the sensors has failed.
A method of identifying a faulty sensor in a process having multiple sensors each of which produces an associated sensor output signal comprising the steps of:
- using a correlation analysis to determine a set of sensor estimate signals from a combination of a plurality of the sensor output signals;
- calculating a residual indicative of a difference between the sensor output signals and the set of sensor estimate signals;
- determining if one of the sensors has failed from the residual;
- calculating a validity index as a function of the residual for each of the sensors when one of the sensors has been determined to have failed;
- and
- identifying the particular sensor which has failed from the calculated validity indexes.
An apparatus which detects a faulty sensor within a process control system having a set of sensors each of which produces an associated sensor output signal, the apparatus comprising:
- means for producing a set of sensor estimate signals from a combination of a plurality of the sensor output signals wherein each sensor estimate signal comprises an estimate of the output of a different one of the sensors;
- means for determining a validity index for one of the set of sensors as a function of a residual which is indicative of a difference between the sensor estimate signals and the sensor output signals;
- and
- means for ascertaining if the one of the set of sensors has failed from the determined validity index.
An apparatus for identifying a faulty sensor in a process having multiple sensors each of which produces an associated sensor output signal comprising:
- means for implementing a correlation analysis to determine a set of sensor estimate signals from a combination of a plurality of the sensor output signals;
- means for calculating a residual indicative of a difference between the sensor output signals and the set of sensor estimate signals;
- means for determining if one of the sensors has failed from the residual;
- means for developing a validity index as a function of the residual for each of the sensors when one of the sensors has been determined to have failed;
- and
- means for identifying a particular sensor which has failed from the calculated validity indexes.
Dependencies are inferred from the claim text.