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US7451004B2 Expired / Lapsed US ⏱️ 0.0 years remaining

On-line adaptive model predictive control in a process control system

Assignee: Fisher Rosemount Systems Inc
•
Filing: 2005-09-30
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Granted: 2008-11-11
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Expires: 2025-09-30
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Abstract

Abstract A method of creating and using an adaptive DMC type or other MPC controller includes using a model switching technique to periodically determine a process model, such as a parameterized process model, for a process loop on-line during operation of the process. The method then uses the process model to generate an MPC control model and creates and downloads an MPC controller algorithm to an MPC controller based on the new control model while the MPC controller is operating on-line. This technique, which is generally applicable to single-loop MPC controllers and is particularly useful in MPC controllers with a control horizon of one or two, enables an MPC controller to be adapted during the normal operation of the process, so as to change the process model on which the MPC controller is based to thereby account for process changes. The adaptive MPC controller is not computationally expensive and can therefore be easily implemented within a distributed controller of a process control system, while providing the same or in some cases better control than a PID controller, especially in dead time dominant process loops, and in process loops that are subject to process model mismatch within the process time to steady state.

Inventors

  • 👤 Dirk Thiele
  • 👤 Wilhelm K. Wojsznis

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-27 08:46
CPC Classifications
G; G05; G05B; G05B13/00; G05B13/02; G05B13/04; G05B13/048

Claims Analysis

Total Claims: 27
Claim 1
Independent Claim 166 words
A process controller for controlling a process, the process controller comprising: a dynamic matrix control controller having a controller algorithm that uses a gain vector to produce a control signal based on an input signal, the control signal being developed for controlling a process variable; a process model estimation unit coupled to the process to collect process data during the on-line operation of the process and that determines a process model representing the operation of the process from the collected process data, the process model including multiple model parameters including a process dead time parameter; and a controller adaptation unit that uses the process model including the process dead time parameter to calculate a new gain vector for use in the dynamic matrix controller algorithm and that adapts the controller algorithm of the dynamic matrix controller to use the new gain vector, wherein the controller adaptation unit adapts the controller to use the new gain vector while the controller is operating on-line to control the process.
Claim 2
Dependent Claim 166 words
A process controller for controlling a process, the process controller comprising: a dynamic matrix control controller having a controller algorithm that uses a gain vector to produce a control signal based on an input signal, the control signal being developed for controlling a process variable; a process model estimation unit coupled to the process to collect process data during the on-line operation of the process and that determines a process model representing the operation of the process from the collected process data, the process model including multiple model parameters including a process dead time parameter; and a controller adaptation unit that uses the process model including the process dead time parameter to calculate a new gain vector for use in the dynamic matrix controller algorithm and that adapts the controller algorithm of the dynamic matrix controller to use the new gain vector, wherein the controller adaptation unit adapts the controller to use the new gain vector while the controller is operating on-line to control the process.
Claim 3
Dependent Claim 20 words
The process controller of claim 1 , wherein the dynamic matrix control controller is a model predictive control (MPC) controller.
Claim 4
Dependent Claim 15 words
The process controller of claim 2 , wherein the MPC controller is a single-loop controller.
Claim 5
Dependent Claim 23 words
The process controller of claim 3 , wherein the MPC controller includes one or more feedback paths and one or more feedforward paths.
Claim 6
Dependent Claim 19 words
The process controller of claim 4 , wherein the control algorithm uses a control horizon equal to two scans.
Claim 7
Dependent Claim 19 words
The process controller of claim 4 , wherein the control algorithm uses a control horizon equal to one scan.
Claim 8
Dependent Claim 25 words
The process controller of claim 2 , wherein control algorithm includes a penalty on move variable that is altered during operation of the MPC controller.
Claim 9
Dependent Claim 43 words
The process controller of claim 2 , wherein the MPC controller includes a set point target vector filter having a set point target vector filter parameter, and wherein the set point target vector filter parameter is altered during operation of the MPC controller.
Claim 10
Dependent Claim 20 words
The process controller of claim 2 , wherein the process model is a first order plus dead time process model.
Claim 11
Dependent Claim 16 words
The process controller of claim 2 , wherein the process model is a parametric process model.
Claim 12
Dependent Claim 25 words
The process controller of claim 2 , wherein the controller adaptation unit determines a prediction horizon for the control algorithm based on the process model.
Claim 13
Dependent Claim 25 words
The process controller of claim 2 , wherein the controller adaptation unit determines an execution time for the MPC controller based on the process model.
Claim 14
Dependent Claim 49 words
The process controller of claim 2 , wherein the controller adaptation unit determines a time to steady state from the process model and determines a combination of a prediction horizon for the control algorithm and an execution time for the MPC controller based on the time to steady state.
Claim 15
Dependent Claim 31 words
The process controller of claim 2 , wherein the controller adaptation unit determines a value for a penalty on move variable used in the controller algorithm based on the process model.
Claim 16
Dependent Claim 36 words
The process controller of claim 14 , wherein the process model defines a process dead time and the controller adaptation unit determines the value of the penalty on move variable based on the process dead time.
Claim 17
Dependent Claim 78 words
The process controller of claim 1 , wherein the dynamic matrix control controller includes a prediction unit that determines a prediction vector for a set of controlled variables, a prediction error unit that combines the prediction vector with a set point vector to produce a prediction error vector and wherein the controller algorithm multiplies the prediction error vector by the gain vector to produce a change in a control signal to be used to develop the control signal.
Claim 18
Dependent Claim 22 words
The process controller of claim 1 , wherein the controller adaptation unit calculates the new gain vector using a closed form equation.
Claim 19
Dependent Claim 24 words
The process controller of claim 17 , wherein the closed form equation is a function of one or more of the multiple model parameters.
Claim 20
Dependent Claim 21 words
The process controller of claim 18 , wherein the closed form equation includes a term related to a penalty on move.
Claim 21
Dependent Claim 26 words
The process controller of claim 19 , wherein the controller adaptation unit determines the penalty on move as a function of the process dead time parameter.
Claim 22
Dependent Claim 41 words
The process controller of claim 19 , wherein the process model includes a process time constant as one of the process parameters and wherein the controller adaptation unit determines the penalty on move as a function of the process time constant.
Claim 23
Dependent Claim 61 words
The process controller of claim 18 , wherein the controller adaptation unit includes a step response model generation unit that generates a step response model from the multiple model parameters of the process model, the step response model having a set of step response model gains, and wherein the closed form equation is a function of the step response model gains.
Claim 24
Dependent Claim 15 words
The process controller of claim 1 , wherein the new gain vector comprises a matrix.
Claim 25
Dependent Claim 15 words
The process controller of claim 1 , wherein the new gain vector comprises a scalar.
Claim 26
Dependent Claim 192 words
A process controller for controlling a process, the process controller comprising: a dynamic matrix control controller having a controller algorithm that uses a gain vector to produce a control signal based on an input signal, the control signal being developed for controlling a process variable; a process model estimation unit coupled to the process to collect process data during the on-line operation of the process and that determines a process model representing the operation of the process from the collected process data; and a controller adaptation unit that uses the process model to calculate a new gain vector for use in the dynamic matrix controller algorithm and that adapts the controller algorithm of the dynamic matrix controller to use the new gain vector, wherein the controller adaptation unit adapts the controller to use the new gain vector while the controller is operating on-line to control the process; wherein the dynamic matrix control controller is a single-loop, model predictive control (MPC) controller that includes one or more feedback paths and one or more feedforward paths and wherein the control algorithm uses a control horizon at least ten times shorter than a prediction horizon.
Claim 27
Dependent Claim 192 words
A process controller for controlling a process, the process controller comprising: a dynamic matrix control controller having a controller algorithm that uses a gain vector to produce a control signal based on an input signal, the control signal being developed for controlling a process variable; a process model estimation unit coupled to the process to collect process data during the on-line operation of the process and that determines a process model representing the operation of the process from the collected process data; and a controller adaptation unit that uses the process model to calculate a new gain vector for use in the dynamic matrix controller algorithm and that adapts the controller algorithm of the dynamic matrix controller to use the new gain vector, wherein the controller adaptation unit adapts the controller to use the new gain vector while the controller is operating on-line to control the process; wherein the dynamic matrix control controller is a single-loop, model predictive control (MPC) controller that includes one or more feedback paths and one or more feedforward paths and wherein the control algorithm uses a control horizon at least ten times shorter than a prediction horizon.

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USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 2011-11-11 2012-05-12 2012-11-11 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2015-11-11 2016-05-12 2016-11-11 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2019-11-11 2020-05-12 2020-11-11 $7700.00 Window Closed / Lapsed

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