US3798426A
Expired / Lapsed
US
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Pattern evaluation method and apparatus for adaptive control
Assignee: Schneider Electric Systems USA Inc
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Filing: 1971-12-20
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Granted: 1974-03-19
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Expires: 1991-12-20
Abstract
Abstract A method is provided for automatic adaptation of process controller parameters according to the requirements of a nonlinear process in order to achieve optimum control action. This method evaluates the response of a measured process variable to upset in the form of a change in set point or load. The upset initiates the adaptation procedure, which determines evaluation intervals related to process dead time and lag characteristics as evidenced by the response of the measured variable over predetermined portions of said upset; the deviation in the measured variable from set point or related demand reference is examined over the evaluation intervals and preferably integrated, the integrated error result being indicative of a required proportional gain change in the case of one type of evaluation interval and indicative of a required reset gain change in another type of evaluation interval. Proportional and reset gains are altered in accordance with this procedure until the gains are optimized as evidenced by maximum conformity to the demand references of the measured variable response to upsets generally.
Inventors
- 👤 E Bristol
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:29
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/48; G06G7/66; G05; G05B; G05B13/00; G05B13/02; G05B13/0205; G05B13/024
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
135 words
A method of operating a set point control system to improve system response to upsets to a measured variable by automatically adapting a parameter of said control system, by the steps of: a. measuring a time varying characteristic of the response of the measured variable to an upset during a preliminary portion of said response; b. generating a first gating signal to define a first evaluation time interval subsequent to said preliminary portion based on the results of step (a), said interval being suitable for evaluation of the effect on the response of the parameter to be adapted; c. measuring the deviation of said response from a preselected level during said time interval; and d. adjusting said parameter based on the results of step (c) to reduce said deviation in said response to subsequent upsets.
Claim 2
Independent Claim
135 words
A method of operating a set point control system to improve system response to upsets to a measured variable by automatically adapting a parameter of said control system, by the steps of: a. measuring a time varying characteristic of the response of the measured variable to an upset during a preliminary portion of said response; b. generating a first gating signal to define a first evaluation time interval subsequent to said preliminary portion based on the results of step (a), said interval being suitable for evaluation of the effect on the response of the parameter to be adapted; c. measuring the deviation of said response from a preselected level during said time interval; and d. adjusting said parameter based on the results of step (c) to reduce said deviation in said response to subsequent upsets.
Claim 3
Dependent Claim
40 words
The method of claim 1 wherein step (a) further includes the steps of: e. determining the amplitude of the upset; and f. measuring the response time interval required for the measured variable to complete a predetermined portion of the response.
Claim 4
Dependent Claim
29 words
The method of claim 2 wherein the amplitude determined in step (e) is the difference between the set point level before upset and the set point level after upset.
Claim 5
Dependent Claim
34 words
The method of claim 2 wherein the amplitude determined in step (e) is the difference between the set point level and the peak of the response of the measured variable to a load change.
Claim 6
Dependent Claim
87 words
The method of claim 2 wherein step (f) includes the steps of: g. determining a first point in time when the response of the measured variable reaches a first predetermined level related to the amplitude of the upset from step (e); h. determining a second point in time when the response of the measured variable reaches a second predetermined level related to the amplitude of the upset from step (e); and i. clocking from said first point to said second point to measure said response time interval.
Claim 7
Dependent Claim
59 words
The method of claim 5 wherein step (b) includes the steps of: j. calculating the beginning of said evaluation interval by multiplying the magnitude of the response time interval obtained in step (i) by a first constant; and k. calculating the magnitude of the evaluation interval by multiplying the magnitude of the response time interval by a second constant.
Claim 8
Dependent Claim
86 words
The method of claim 6 including the steps of: l. generating a second gating signal to define a second evaluation time interval based on the results of step (a) suitable for evaluation of the effect on the response of a second parameter to be adapted; m. measuring the deviation between the response of the measured variable and a second reference level related to the set point during the second evaluation interval; and n. adjusting said second parameter on the basis of the results of step (m).
Claim 9
Dependent Claim
21 words
The method of claim 7 wherein the second evaluation interval is immediately subsequent to the end of the first evaluation interval.
Claim 10
Dependent Claim
20 words
The method of claim 7 wherein the second evaluation interval includes at least a portion of the first evaluation interval.
Claim 11
Dependent Claim
38 words
The method of claim 6 wherein step (c) includes the step of: o. integrating the deviation between the response of the measured variable and a predetermined reference level related to the set point during the first evaluation interval.
Claim 12
Dependent Claim
142 words
In a set point control system for controlling a measured variable in a process, the method of operating control device in said system to improve system response to upsets to the measured variable by automatically adapting at least one parameter in said control system in response to an upset, by the steps of: sensing the amplitude of the upset to the measured variable, clocking to determine at least one response time interval related to the time said measured variable reaches a predetermined intermediate level, determining at least one evaluation interval subsequent to said response time interval on the basis of said clocking thereof, evaluating the measured variable deviation from a selected reference level at least at some time during the period of said evaluation interval, and adjusting said parameter of said control system on the basis of the results of said evaluating.
Claim 13
Dependent Claim
142 words
In a set point control system for controlling a measured variable in a process, the method of operating control device in said system to improve system response to upsets to the measured variable by automatically adapting at least one parameter in said control system in response to an upset, by the steps of: sensing the amplitude of the upset to the measured variable, clocking to determine at least one response time interval related to the time said measured variable reaches a predetermined intermediate level, determining at least one evaluation interval subsequent to said response time interval on the basis of said clocking thereof, evaluating the measured variable deviation from a selected reference level at least at some time during the period of said evaluation interval, and adjusting said parameter of said control system on the basis of the results of said evaluating.
Claim 14
Dependent Claim
23 words
The method of claim 11 including the steps of: detection of excess overshoot, and immediate reduction in the controller parameter upon such detection.
Claim 15
Dependent Claim
62 words
The method of claim 11 in which said upset is in the form of a load change causing a deviation of the measured variable from set point, further including the step of: modifying the load change deviation to appear as a set point change deemed to occur at the time of the maximum deviation during the first half cycle of such upset.
Claim 16
Dependent Claim
35 words
The method of claim 11 in which said upset is in the form of a set point change, wherein: the amplitude sensed is the difference between the initial set point and the changed set point.
Claim 17
Dependent Claim
23 words
The method of claim 14 wherein the clocking step includes: clocking a first said response time interval from the occurrence of said upset.
Claim 18
Dependent Claim
28 words
The method of claim 15 wherein the clocking step further includes: clocking a second said response time interval from the termination of said first said response time interval.
Claim 19
Dependent Claim
52 words
The method of claim 14 wherein said clocking step includes: clocking a closed loop lag response time interval between the times said measured variable reaches a first intermediate level corresponding to one-fourth of the amplitude of the upset, and a second intermediate level corresponding to three-fourths of the amplitude of the upset.
Claim 20
Dependent Claim
25 words
The method of claim 11 wherein said evaluation interval determining step includes: determining two evaluation intervals related to said response time interval and subsequent thereto.
Claim 21
Dependent Claim
31 words
The method of claim 18 wherein the evaluation step further includes: integrating the deviation of the measured variable from a first selected reference level during the first of said evaluation intervals.
Claim 22
Dependent Claim
29 words
The method of claim 19 wherein the evaluation interval further includes: integrating the deviation of the measured variable from a second selected reference level during said second evaluation interval.
Claim 23
Dependent Claim
57 words
The method of claim 20 further including the steps of: computing a proportional gain adjustment based on said integration during the first evaluation interval, computing a reset gain adjustment based on said integration during the second interval, and wherein said adjusting step includes: adjusting the parameters of the control system in accordance with said computed gain adjustments.
Claim 24
Dependent Claim
203 words
In a set point control system the method of automatically adapting at least one gain setting in said control system in response to an upset to a measured variable, by the steps of: sensing the amplitude of the upset, determining the intermediate levels in accordance with predetermined portions of said amplitude of said upset, clocking to determine at least one response time interval related to the time said measured variable acquires an amplitude equivalent to a particular one of said intermediate levels, calculating at least one computed interval from said response time interval, relating said computed interval to said response time interval to determine an evaluation interval subsequent to said response time interval so that said evaluation interval is suitable to evaluate the response of said measured variable to said upset, examining in the period of said evaluation interval the deviation between said measured variable and a selected reference level related to said set point, computing a gain adjustment based upon the results of said examination and, adjusting said gain setting in said control system with said gain adjustment to effect an adaptation of said gain setting of said control system to modify the response of said measured variable to any subsequent upsets.
Claim 25
Dependent Claim
203 words
In a set point control system the method of automatically adapting at least one gain setting in said control system in response to an upset to a measured variable, by the steps of: sensing the amplitude of the upset, determining the intermediate levels in accordance with predetermined portions of said amplitude of said upset, clocking to determine at least one response time interval related to the time said measured variable acquires an amplitude equivalent to a particular one of said intermediate levels, calculating at least one computed interval from said response time interval, relating said computed interval to said response time interval to determine an evaluation interval subsequent to said response time interval so that said evaluation interval is suitable to evaluate the response of said measured variable to said upset, examining in the period of said evaluation interval the deviation between said measured variable and a selected reference level related to said set point, computing a gain adjustment based upon the results of said examination and, adjusting said gain setting in said control system with said gain adjustment to effect an adaptation of said gain setting of said control system to modify the response of said measured variable to any subsequent upsets.
Claim 26
Dependent Claim
36 words
The method of claim 22 wherein the step of determining intermediate levels includes the step of: determining a first and a second intermediaTe level in accordance with one-quarter and three-quarters of said amplitude of said upset.
Claim 27
Dependent Claim
35 words
The method of claim 22 in which said upset is in the form of a set point change wherein: the amplitude sensed is the difference between the initial set point and the changed set point.
Claim 28
Dependent Claim
61 words
The method of claim 22 in which said upset is in the form of a load change causing the deviation of the measured variable from set point, further including the step of: modifying the load change deviation to appear as a set point change deemed to occur at the time of maximum deviation during the first half cycle of such upset.
Claim 29
Dependent Claim
90 words
The method of claim 22 wherein the clocking step further includes the steps of: clocking a first said response time interval from the occurrence of said upset to the time said measured variable acquires an amplitude related to an earlier reached one of said intermediate levels, and clocking a second said response time interval from the time said measured variable acquires an amplitude related to an earlier reached of said intermediate levels to the time said measured variable acquires an amplitude related to a later reached of said intermediate levels.
Claim 30
Dependent Claim
106 words
An adaptation device to be used with a control system having an adjustable proportional band and measurement and set point inputs, said device comprising: means for determining a response time interval during an initial portion of a response of said control system to an upset; computational means to choose an evaluation interval based on said response time interval suitable for investigating the effects on the response of the proportional band; means for detecting the error between the response during said evaluation interval and a desired level; and means responsive to said error detecting means for adjusting said proportional band to reduce said error for subsequent upsets.
Claim 31
Dependent Claim
106 words
An adaptation device to be used with a control system having an adjustable proportional band and measurement and set point inputs, said device comprising: means for determining a response time interval during an initial portion of a response of said control system to an upset; computational means to choose an evaluation interval based on said response time interval suitable for investigating the effects on the response of the proportional band; means for detecting the error between the response during said evaluation interval and a desired level; and means responsive to said error detecting means for adjusting said proportional band to reduce said error for subsequent upsets.
Claim 32
Dependent Claim
86 words
The device of claim 27, wherein said control system further includes an adjustable reset band, said device further comprising: computational means to choose a second evaluation interval based on said response time interval suitable for investigating the effects on the response of the reset band; second means for detecting the error between said response and a second desired level during said second evaluation interval; and means responsive to said second error detecting means for adjusting said reset band to further reduce said error for subsequent upsets.
Claim 33
Dependent Claim
100 words
An adaptation device, for use with a control system of the type having at least one adjustable parameter, comprising: means for detecting the slope of a preliminary portion of the response of a measured variable of the control system to an upset; means to determine an evaluation interval based upon said slope suitable for evaluating the effect on the response shape of the parameter to be adapted, a comparator active during said evaluation interval to determine the error between said response and a desired level; and means responsive to said comparator to adjust said parameter based on said error determination.
Claim 34
Dependent Claim
100 words
An adaptation device, for use with a control system of the type having at least one adjustable parameter, comprising: means for detecting the slope of a preliminary portion of the response of a measured variable of the control system to an upset; means to determine an evaluation interval based upon said slope suitable for evaluating the effect on the response shape of the parameter to be adapted, a comparator active during said evaluation interval to determine the error between said response and a desired level; and means responsive to said comparator to adjust said parameter based on said error determination.
Claim 35
Dependent Claim
104 words
Apparatus for adapting a process controller in response to an upset to provide optimal matching of the controller characteristics to a process, comprising: first means for generating a first signal related to the response time interval required for a measured variable to complete a predetermined portion of its recovery from an upset; second means for determining an evaluation interval based on said first signal suitable for evaluating the effects on the response of a particular controller characteristic; third means for generating a second signal to adapt said controller characteristic related to the difference between the response and a reference level during said evaluation interval.
Claim 36
Dependent Claim
104 words
Apparatus for adapting a process controller in response to an upset to provide optimal matching of the controller characteristics to a process, comprising: first means for generating a first signal related to the response time interval required for a measured variable to complete a predetermined portion of its recovery from an upset; second means for determining an evaluation interval based on said first signal suitable for evaluating the effects on the response of a particular controller characteristic; third means for generating a second signal to adapt said controller characteristic related to the difference between the response and a reference level during said evaluation interval.
Claim 37
Dependent Claim
77 words
Apparatus as claimed in claim 30 wherein said first means includes: means for sensing the magnitude of said upset; means for generating third and fourth Signals related to said magnitude multiplied by first and second constants; means for determining first and second points in time during said recovery when said measurement signal equals said third and fourth signals respectively; and means for clocking the time between said first and second points to measure said response time interval.
Claim 38
Dependent Claim
58 words
Apparatus as claimed in claim 31 wherein said second means includes: means for determining third and fourth points in time subsequent to said second point by periods of time related to said response time interval multiplied by third and fourth constants respectively, said third and fourth points serving to define the beginning and end of said evaluation interval.
Claim 39
Dependent Claim
28 words
Apparatus as claimed in claim 32 wherein said third means includes: an integrator for integrating the difference between the response and the reference level during said evaluation interval.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |