US5680409A — Method and apparatus for detecting and identifyin…

Claim 1

Independent Claim 124 words

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.

Claim 2

Independent Claim 124 words

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.

Claim 3

Dependent Claim 46 words

The method of claim 1, wherein the step of determining the validity index further comprises the step of determining the validity index as a function of a further residual indicative of another measure of the difference between the sensor estimate signals and the sensor output signals.

Claim 4

Dependent Claim 34 words

The method of claim 2, wherein the step of determining the validity index comprises the step of determining the validity index as a function of a ratio of the residual and the further residual.

Claim 5

Dependent Claim 49 words

The method of claim 3, wherein the step of determining the validity index comprises the step of using a residual, the value of which is a measure of the sum of the squared differences between the sensor estimate signals and the sensor output signals, to determine the validity index.

Claim 6

Dependent Claim 43 words

The method of claim 3, wherein the step of determining the validity index comprises the step of using a further residual, the value of which is dependent upon the sensor for which the validity index is being determined, to determine the validity index.

Claim 7

Dependent Claim 79 words

The method of claim 3, wherein the step of producing the set of sensor estimate signals includes the step of using a set of weighting coefficients developed for the process control system to produce the sensor estimate signals and the step of determining the validity index comprises the step of using a further residual, the value of which is dependent upon an element of a cross-correlation matrix associated with the set of weighting coefficients, to determine the validity index.

Claim 8

Dependent Claim 105 words

The method of claim 3, wherein the step of producing the set of sensor estimate signals includes the step of using a set of weighting coefficients developed for the process control system to calculate the sensor estimate signals and the step of determining the validity index comprises the step of calculating a validity index η i for an ith sensor S i as: ##EQU13## wherein: x i =the sensor output signal of the ith sensor; x i =the sensor estimate signal associated with the ith sensor; n=the number of sensors; and c ii & c hh =cross-correlation coefficients developed from the set of weighting coefficients.

Claim 9

Dependent Claim 40 words

The method of claim 1, wherein the step of producing the set of sensor estimate signals includes the step of using a set of weighting coefficients developed by a principal component analysis to produce the set of sensor estimate signals.

Claim 10

Dependent Claim 36 words

The method of claim 8, wherein the step of producing the set of sensor estimate signals includes the step of calculating an asymptotic value of a sensor estimate signal for one of the set of sensors.

Claim 11

Dependent Claim 86 words

The method of claim 8, wherein the step of producing the set of sensor estimate signals includes the step of calculating the asymptotic value of a sensor estimate signal x i for a sensor S i which would be developed by an iterative routine that recalculates the value of the sensor estimate signal x i during each iteration using principal component analysis wherein, in each iteration, an input of the iterative routine is replaced with the sensor estimate signal x i calculated in a previous iteration.

Claim 12

Dependent Claim 46 words

The method of claim 8, wherein the step of determining the validity index comprises the step of using a residual, the value of which is a function of an element of a cross-correlation matrix associated with the set of weighting coefficients, to determine the validity index.

Claim 13

Dependent Claim 41 words

The method of claim 8, wherein the step of producing the set of sensor estimate signals includes the step of using a set of weighting coefficients developed by a non-linear principal component analysis to produce the set of sensor estimate signals.

Claim 14

Dependent Claim 60 words

The method of claim 1, wherein the step of determining the validity index comprises the step of using a residual, the value of which is a function of the difference between the sensor estimate signals and the sensor output signals with one of the sensor output signals replaced by one of the sensor estimate signals, to determine the validity index.

Claim 15

Dependent Claim 14 words

The method of claim 1, further comprising the step of filtering the validity index.

Claim 16

Dependent Claim 25 words

The method of claim 14, wherein the step of filtering the validity index comprises the step of filtering the validity index using an iterative routine.

Claim 17

Dependent Claim 25 words

The method of claim 14, wherein the step of filtering the validity index comprises the step of filtering the validity index in an adaptive manner.

Claim 18

Dependent Claim 33 words

The method of claim 1, further including the step of notifying an operator that the one of the sensors has failed when the one of the sensors has been ascertained to have failed.

Claim 19

Dependent Claim 81 words

The method of claim 1, wherein the process control system controls a process in accordance with the sensor output signals and further including the step of replacing the sensor output signal of a sensor which has been ascertained to have failed with the sensor estimate signal associated with the sensor which has been ascertained to have failed before the process control system uses the sensor output signal of the sensor which has been ascertained to have failed in controlling the process.

Claim 20

Independent Claim 118 words

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.

Claim 21

Independent Claim 118 words

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.

Claim 22

Dependent Claim 46 words

The method of claim 19, wherein the step of calculating the validity index comprises the step of determining the validity index as a function of a further residual which is indicative of another difference between the set of sensor estimate signals and the sensor output signals.

Claim 23

Dependent Claim 34 words

The method of claim 20, wherein the step of determining the validity index comprises the step of determining the validity index as a function of the ratio of the residual and the further residual.

Claim 24

Dependent Claim 44 words

The method of claim 21, wherein the step of determining the validity index comprises the step of using a further residual, the value of which is a function of the sensor for which the validity index is being determined, to determine the validity index.

Claim 25

Dependent Claim 86 words

The method of claim 19, wherein the step of producing the set of sensor estimate signals includes the step of calculating the asymptotic value of a sensor estimate signal x i for a sensor S i which would be developed by an iterative routine that recalculates the value of the sensor estimate signal x i during each iteration using principal component analysis wherein, in each iteration, an input of the iterative routine is replaced with the sensor estimate signal x i calculated in a previous iteration.

Claim 26

Independent Claim 121 words

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.

Claim 27

Independent Claim 121 words

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.

Claim 28

Dependent Claim 39 words

The apparatus of claim 24, wherein the determining means includes means for calculating the validity index as a function of a further residual which is indicative of another difference between the sensor estimate signals and the sensor output signals.

Claim 29

Dependent Claim 26 words

The apparatus of claim 25, wherein the calculating means calculates the validity index as a function of a ratio of the residual and the further residual.

Claim 30

Dependent Claim 41 words

The apparatus of claim 25, wherein the calculating means calculates the validity index as a function of the further residual, wherein the further residual has a value which is dependent upon the sensor for which the validity index is being determined.

Claim 31

Dependent Claim 63 words

The apparatus of claim 25, wherein the producing means uses a set of weighting coefficients developed for the process control system to calculate the sensor estimate signals and the calculating means calculates the validity index as a function of the further residual, wherein the further residual has a value which is dependent upon a cross-correlation coefficient associated with the set of weighting coefficients.

Claim 32

Dependent Claim 99 words

The apparatus of claim 24, wherein the producing means produces the set of sensor estimate signals using a set of weighting coefficients developed by a principal component analysis and includes means for calculating an asymptotic value of a sensor estimate signal x i for the ith sensor S i which would be developed by an iterative routine that recalculates the value of the sensor estimate signal x i during each iteration using principal component analysis wherein, in each iteration, an input of the iterative routine is replaced with the sensor estimate signal x i calculated in a previous iteration.

Claim 33

Dependent Claim 89 words

The apparatus of claim 24, wherein the producing means uses a set of weighting coefficients developed for the process control system to produce the sensor estimate signals and the determining means includes means for calculating a validity index η i for an ith sensor S i as: ##EQU14## wherein: x i =the sensor output signal of the ith sensor; x i =the sensor estimate signal associated with the ith sensor; n=the number of sensors; and c ii & c hh =cross-correlation coefficients developed from the set of weighting coefficients.

Claim 34

Dependent Claim 13 words

The apparatus of claim 24, further comprising means for filtering the validity index.

Claim 35

Dependent Claim 17 words

The apparatus of claim 31, wherein the filtering means comprises means for iteratively filtering the validity index.

Claim 36

Dependent Claim 17 words

The apparatus of claim 31, wherein the filtering means comprises means for adaptively filtering the validity index.

Claim 37

Dependent Claim 34 words

The apparatus of claim 24, further including means for notifying an operator of the identity of the sensor which has failed when the ascertaining means ascertains that the one of the sensors has failed.

Claim 38

Dependent Claim 80 words

The apparatus of claim 24, wherein the process control system controls a process in accordance with the sensor output signals and further including means for replacing the sensor output signal of a sensor which has been ascertained to have failed with the sensor estimate signal associated with the sensor which has been ascertained to have failed before the process control system uses the sensor output signal of the sensor which has been ascertained to have failed in controlling the process.

Claim 39

Independent Claim 125 words

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.

Claim 40

Independent Claim 125 words

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.

Claim 41

Dependent Claim 42 words

The apparatus of claim 36, wherein the developing means develops the validity index for a sensor as a function of the residual and a further residual which is indicative of another difference between the sensor estimate signals and the sensor output signals.

Claim 42

Dependent Claim 29 words

The apparatus of claim 37, wherein the developing means develops the validity index for a sensor as a function of the ratio of the residual and the further residual.

Claim 43

Dependent Claim 87 words

The apparatus of claim 36, wherein the process control system controls a process in accordance with the sensor output signals and further including means for replacing the sensor output signal of the particular sensor which has been identified to have failed by the identifying means with the sensor estimate signal associated with the particular sensor which has been identified to have failed before the process control system uses the sensor output signal of the particular sensor which has been identified to have failed in controlling the process.

Claim 44

Dependent Claim 30 words

The apparatus of claim 39, further including means for notifying an operator of the identity of the particular sensor which has been identified to have failed by the identifying means.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-10-20	2001-04-21	2001-10-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-10-20	2005-04-21	2005-10-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-10-20	2009-04-21	2009-10-21	$7700.00	Window Closed / Lapsed

Method and apparatus for detecting and identifying faulty sensors in a process

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag