US5355305A
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US
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Pattern recognition adaptive controller
Assignee: Johnson Controls Technology Co
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Filing: 1992-10-29
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Granted: 1994-10-11
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Expires: 2012-10-29
Abstract
Abstract A pattern recognition adaptive controller configured to dynamically adjust proportional gain and integral time control parameters to minimize integrated absolute errors between a setpoint and a monitored controlled variable. The pattern recognition adaptive controller receives a sampled signal representative of the controlled variable, and determines a smoothed signal based on the sampled signal. The controller characterizes a disturbance in the smoothed signal by a damping factor and a closed loop response time. When a significant load disturbance or setpoint change occurs, the controller estimates an optimal gain based on the damping factor, and an optimal integral time based on the response time. The estimated optimal gain and estimated optimal integral time are used to determining a new gain and a new integral time values, to which the control parameters of the controller are then set.
Inventors
- 👤 John E. Seem
- 👤 Howard J. Haugstad
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:12
CPC Classifications
G; G05; G05B; G05B11/00; G05B11/01; G05B11/36; G05B11/42; G05B13/00; G05B13/02; G05B13/0205; G05B13/024
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
139 words
A method of dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising the steps of: sampling a feedback signal representative of a controlled variable of the process to generate a sampled signal; generating a smoothed signal based on the sampled signal; determining an estimated noise level of the sampled signal; determining a tune noise band based on the estimated noise level and the smoothed signal; adjusting the gain and integral time values used by the controller if either the difference between a previous setpoint value and a current setpoint value, or the difference between the current setpoint value and the smoothed signal, falls outside the tune noise band; and utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 2
Independent Claim
139 words
A method of dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising the steps of: sampling a feedback signal representative of a controlled variable of the process to generate a sampled signal; generating a smoothed signal based on the sampled signal; determining an estimated noise level of the sampled signal; determining a tune noise band based on the estimated noise level and the smoothed signal; adjusting the gain and integral time values used by the controller if either the difference between a previous setpoint value and a current setpoint value, or the difference between the current setpoint value and the smoothed signal, falls outside the tune noise band; and utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 3
Dependent Claim
55 words
The method of claim 1 wherein the step of generating a smooth signal includes determining a smoothed sample value based upon fitting a quadratic function through a first plurality of evenly spaced points, and estimating the slope of the sampled signal based upon fitting a quadratic function through a second plurality of evenly spaced points.
Claim 4
Dependent Claim
56 words
The method of claim 1 wherein the step of determining an estimated noise level includes determining a current noise level based on the difference between the sampled signal and the smoothed signal, and determining a long-term average noise level based on an exponentially weighted moving average of the current noise level and previously determined noise levels.
Claim 5
Dependent Claim
42 words
The method of claim 1 wherein the step of determining a tune noise band includes determining a long term average noise level, and wherein the tune noise band is determined based upon the long-term average noise level and the current setpoint value.
Claim 6
Independent Claim
148 words
An apparatus for dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising: means for sampling a feedback signal representative of a controlled variable of the process to generate a sampled signal; means for generating a smoothed signal based on the sampled signal; means for determining an estimated noise level of the sampled signal; means for determining a tune noise band based on the estimated noise level and the smoothed signal; means for adjusting the gain and integral time values used by the controller if either the difference between a previous setpoint value and a current setpoint value, or the difference between the current setpoint value and the smoothed signal, falls outside the tune noise band; and means for utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 7
Independent Claim
148 words
An apparatus for dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising: means for sampling a feedback signal representative of a controlled variable of the process to generate a sampled signal; means for generating a smoothed signal based on the sampled signal; means for determining an estimated noise level of the sampled signal; means for determining a tune noise band based on the estimated noise level and the smoothed signal; means for adjusting the gain and integral time values used by the controller if either the difference between a previous setpoint value and a current setpoint value, or the difference between the current setpoint value and the smoothed signal, falls outside the tune noise band; and means for utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 8
Dependent Claim
59 words
The apparatus of claim 5 wherein the means for generating a smooth signal includes means for determining a smoothed sample value based upon fitting a quadratic function through a first plurality of evenly spaced points, and means for estimating the slope of the sampled signal based upon fitting a quadratic function through a second plurality of evenly spaced points.
Claim 9
Dependent Claim
60 words
The apparatus of claim 5 wherein the means for determining an estimated noise level includes means for determining a current noise level based on the difference between the sampled signal and the smoothed signal, and means for determining a long-term average noise level based on an exponentially weighted moving average of the current noise level and previously determined noise levels.
Claim 10
Dependent Claim
28 words
The apparatus of claim 5 wherein the means for determining a tune noise band includes means for determining a long-term average noise level and the current setpoint value.
Claim 11
Independent Claim
272 words
A method of dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising the steps of: sampling a feedback signal representative of a controlled variable of the process to generate a sampled signal; generating a smoothed signal based on the sampled signal; determining an estimated noise level of the sampled signal; determining a tune noise band based on the estimated noise level and the smoothed signal; determining whether a significant setpoint change has occurred by comparing the tune noise band to the difference between a previous setpoint value and a current setpoint value; determining whether a significant load disturbance has occurred by comparing the tune noise band to the difference between the current setpoint value and the smoothed signal; determining a damping factor based on the slope of the smoothed signal; determining a closed loop response time based on the height of the smoothed signal; determining an average disturbance size; estimating an optimal gain based on the damping factor; estimating an optimal integral time based on the response time; determining a new gain and a new integral time based on the estimated optimal gain, the estimated optimal integral time, the current gain and integral time values used in the controller, a signal-to-noise ratio of the sampled signal, and the size of a current load disturbance or setpoint change relative to the average disturbance size; setting the gain and integral time of the controller to the new gain and the new integral time; and utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 12
Independent Claim
272 words
A method of dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising the steps of: sampling a feedback signal representative of a controlled variable of the process to generate a sampled signal; generating a smoothed signal based on the sampled signal; determining an estimated noise level of the sampled signal; determining a tune noise band based on the estimated noise level and the smoothed signal; determining whether a significant setpoint change has occurred by comparing the tune noise band to the difference between a previous setpoint value and a current setpoint value; determining whether a significant load disturbance has occurred by comparing the tune noise band to the difference between the current setpoint value and the smoothed signal; determining a damping factor based on the slope of the smoothed signal; determining a closed loop response time based on the height of the smoothed signal; determining an average disturbance size; estimating an optimal gain based on the damping factor; estimating an optimal integral time based on the response time; determining a new gain and a new integral time based on the estimated optimal gain, the estimated optimal integral time, the current gain and integral time values used in the controller, a signal-to-noise ratio of the sampled signal, and the size of a current load disturbance or setpoint change relative to the average disturbance size; setting the gain and integral time of the controller to the new gain and the new integral time; and utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 13
Dependent Claim
16 words
The method of claim 9 further comprising the step of determining whether the actuator is saturated.
Claim 14
Dependent Claim
55 words
The method of claim 9 wherein the step of generating a smooth signal includes determining a smoothed sample value based upon fitting a quadratic function through a first plurality of evenly spaced points, and estimating the slope of the sampled signal based upon fitting a quadratic function through a second plurality of evenly spaced points.
Claim 15
Dependent Claim
56 words
The method of claim 9 wherein the step of determining an estimated noise level includes determining a current noise level based on the difference between the sampled signal and the smoothed signal, and determining a long-term average noise level based on an exponentially weighted moving average of the current noise level and previously determined noise levels.
Claim 16
Dependent Claim
24 words
The method of claim 12 wherein the tune noise band is determined based upon the long-term average noise level and the current setpoint value.
Claim 17
Dependent Claim
148 words
The method of claim 9 wherein the damping factor is determined, when the smoothed signal is underdamped, according to the formula: ##EQU14## where, for setpoint changes, S 1 is the maximum of the absolute value of the slope of the smoothed signal between the time the smoothed signal falls outside a tune noise range and the time of a first extremum, and S 2 is the maximum of the absolute value of the slope of the smoothed signal between the time of the first extremum and a second extremum, and for load disturbances, S 1 is the maximum of the absolute value of the slope of the smoothed signal between the time of the first extremum and the second extremum, and S 2 is the maximum of the absolute value of the slope of the smoothed signal between the time of the second extremum and a third extremum.
Claim 18
Dependent Claim
114 words
The method of claim 9 wherein the closed loop response time is determined, when the smoothed signal is underdamped, according to the formula: ##EQU15## where θ is the closed loop response time, T is the sampling interval, h is the height of the response, and for setpoint changes, S 1 is the maximum of the absolute value of the slope of the smoothed signal between the time the smoothed signal falls outside a tune noise range and the time of a first extremum, and for load disturbances, S 1 is the maximum of the absolute value of the slope of the smoothed signal between the time of the first extremum and a second extremum.
Claim 19
Dependent Claim
30 words
The method of claim 9 wherein the average disturbance size is determined by calculating an exponentially weighted moving average of the difference between the previous setpoint and a first extremum.
Claim 20
Dependent Claim
70 words
The method of claim 9 wherein the step of estimating an optimal gain based on the damping factor includes determining the ratio of the estimated optimal gain to the present gain is according to the formula: ##EQU16## where K opt is the estimated optimal gain, K is the present value of the gain used in the controller D slope , and the A n coefficients are determined by linear regression.
Claim 21
Dependent Claim
71 words
The method of claim 9 wherein the step of estimating an optimal integral time based on the response time includes determining the ratio of the estimated optimal integral time to the actual sampling interval according to the formula: ##EQU17## where T i ,opt is the estimated optimal integral time, T is the sampling interval, θ is the closed loop response time, and the B n coefficients are determined by linear regression.
Claim 22
Independent Claim
164 words
A apparatus for dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising: means for sensing the variable and generating a feedback signal representative of the variable; means for determining a damping factor based on the slope of the feedback signal; means for determining a closed loop response time based on the height of the feedback signal; means for estimating an optimal gain based on the damping factor; means for estimating an optimal integral time based on the response time; means for determining a new gain and a new integral time based on the estimated optimal gain, the estimated optimal integral time, and the current gain and integral time values used in the controller; means for setting the gain and integral time of the controller to the new gain and the new integral time; and utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 23
Independent Claim
164 words
A apparatus for dynamically adjusting the control parameters of a proportional gain and integral time controller disposed to control an actuator affecting a process, comprising: means for sensing the variable and generating a feedback signal representative of the variable; means for determining a damping factor based on the slope of the feedback signal; means for determining a closed loop response time based on the height of the feedback signal; means for estimating an optimal gain based on the damping factor; means for estimating an optimal integral time based on the response time; means for determining a new gain and a new integral time based on the estimated optimal gain, the estimated optimal integral time, and the current gain and integral time values used in the controller; means for setting the gain and integral time of the controller to the new gain and the new integral time; and utilizing the adjusted control parameters to control the actuator, thereby causing the controller to affect the process.
Claim 24
Dependent Claim
25 words
The apparatus of claim 19 further comprising: means for sampling the feedback signal; and means for smoothing the feedback signal based on the sampled values.
Claim 25
Dependent Claim
125 words
The apparatus of claim 19 further comprising: means for determining an estimated noise level of the feedback signal; means for determining a tune noise band based on the estimated noise level and the feedback signal; means for determining whether a significant setpoint change has occurred by comparing the tune noise band to the difference between a previous setpoint value and a current setpoint value; means for determining whether a significant load disturbance has occurred by comparing the tune noise band to the difference between the current setpoint value and the feedback signal; and wherein the gain and integral time of the controller are set to the new gain and the new integral time when either a significant setpoint change or a significant load disturbance occurs.
Claim 26
Dependent Claim
50 words
The apparatus of claim 21 further comprising means for determining an average disturbance size, wherein the new gain and new integral time are further based upon a signal-to-noise ratio of the feedback signal and the size of a current load disturbance or setpoint change relative to the average disturbance size.
References Cited (Backward Citations)
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Cited
US4999557A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-10-10 | 1998-04-11 | 1998-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-10 | 2002-04-11 | 2002-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-10-10 | 2006-04-11 | 2006-10-11 | $7700.00 | Window Closed / Lapsed |