Computer method and apparatus for constraining a non-linear approximator of an empirical process
First Claim
1. A non-transitory computer readable memory medium that stores computer executable instructions that when executed by a processor perform model predictive control and optimization of a nonlinear process by implementinga parametric universal nonlinear dynamic approximator for predictive control and optimization of a nonlinear process, comprising:
- a dynamic parameterized model, operable to model the nonlinear process, wherein the dynamic parameterized model receives one or more parameters that are not inputs or outputs of the nonlinear process, andwherein the one or more parameters are outputs of an explicit mapping to a parameter space; and
a nonlinear approximator, operable to explicitly model dependencies of the one or more parameters of the dynamic parameterized model upon operating conditions of the nonlinear process;
wherein the parametric universal nonlinear dynamic approximator is operable to predict process outputs necessary for predictive control and optimization of the nonlinear process, wherein actual measurements of at least one of the process outputs do not exist, by;
operating the nonlinear approximator to;
receive one or more process operating conditions, including one or more process inputs; and
generate values for the one or more parameters of the dynamic parameterized model based on the process operating conditions; and
provide the values for the one or more parameters to the dynamic parameterized model; and
operating the dynamic parameterized model to;
receive the values of the one or more parameters from the nonlinear approximator;
receive the one or more process inputs;
generate one or more predicted process outputs based on the received values of the one or more parameters and the received one or more process inputs; and
store the one or more predicted process outputs;
wherein the parametric universal nonlinear dynamic approximator is operable to be coupled to the nonlinear process, wherein the parametric universal nonlinear dynamic approximator is further operable to be coupled to a control process, wherein the control process is operable to;
a) initialize a parametric universal nonlinear dynamic approximator to a current status of the nonlinear process, comprising process inputs and outputs, by;
initializing inputs to a nonlinear approximator comprised in the parametric universal nonlinear dynamic approximator, wherein the nonlinear approximator is trained to model dependencies of one or more parameters of a dynamic parameterized model of the nonlinear process comprised in the parametric universal nonlinear dynamic approximator upon operating conditions of the nonlinear process;
executing the trained nonlinear approximator to determine initial values for the one or more parameters of the dynamic parameterized model based on the current status of the nonlinear process; and
initializing the parameterized dynamic model with the determined initial values for the one or more parameters;
b) formulate an optimization problem, including specifying an objective function for optimization of the nonlinear process;
c) generate a profile of manipulated variables for the nonlinear process over a control horizon in accordance with the specified objective function for optimization of the nonlinear process;
d) operate the parametric universal nonlinear dynamic approximator in accordance with the generated profile of manipulated variables, thereby generating predicted outputs for the nonlinear process;
e) determine a deviation of the predicted outputs from a desired behavior of the nonlinear process;
f) repeat b)- e) one or more times to determine an optimal profile of manipulated variables in accordance with the specified objective function for optimization of the nonlinear process;
g) operate the nonlinear process in accordance with the optimal profile of manipulated variables, thereby generating process output; and
repeat a)- g) one or more times to dynamically control the nonlinear process.
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Abstract
A constrained non-linear approximator for empirical process control is disclosed. The approximator constrains the behavior of the derivative of a subject empirical model without adversely affecting the ability of the model to represent generic non-linear relationships. There are three stages to developing the constrained non-linear approximator. The first stage is the specification of the general shape of the gain trajectory or base non-linear function which is specified graphically, algebraically or generically and is used as the basis for transfer functions used in the second stage. The second stage of the invention is the interconnection of the transfer functions to allow non-linear approximation. The final stage of the invention is the constrained optimization of the model coefficients such that the general shape of the input/output mappings (and their corresponding derivatives) are conserved.
80 Citations
33 Claims
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1. A non-transitory computer readable memory medium that stores computer executable instructions that when executed by a processor perform model predictive control and optimization of a nonlinear process by implementing
a parametric universal nonlinear dynamic approximator for predictive control and optimization of a nonlinear process, comprising: -
a dynamic parameterized model, operable to model the nonlinear process, wherein the dynamic parameterized model receives one or more parameters that are not inputs or outputs of the nonlinear process, and wherein the one or more parameters are outputs of an explicit mapping to a parameter space; and a nonlinear approximator, operable to explicitly model dependencies of the one or more parameters of the dynamic parameterized model upon operating conditions of the nonlinear process; wherein the parametric universal nonlinear dynamic approximator is operable to predict process outputs necessary for predictive control and optimization of the nonlinear process, wherein actual measurements of at least one of the process outputs do not exist, by; operating the nonlinear approximator to; receive one or more process operating conditions, including one or more process inputs; and generate values for the one or more parameters of the dynamic parameterized model based on the process operating conditions; and provide the values for the one or more parameters to the dynamic parameterized model; and operating the dynamic parameterized model to; receive the values of the one or more parameters from the nonlinear approximator; receive the one or more process inputs; generate one or more predicted process outputs based on the received values of the one or more parameters and the received one or more process inputs; and store the one or more predicted process outputs; wherein the parametric universal nonlinear dynamic approximator is operable to be coupled to the nonlinear process, wherein the parametric universal nonlinear dynamic approximator is further operable to be coupled to a control process, wherein the control process is operable to; a) initialize a parametric universal nonlinear dynamic approximator to a current status of the nonlinear process, comprising process inputs and outputs, by; initializing inputs to a nonlinear approximator comprised in the parametric universal nonlinear dynamic approximator, wherein the nonlinear approximator is trained to model dependencies of one or more parameters of a dynamic parameterized model of the nonlinear process comprised in the parametric universal nonlinear dynamic approximator upon operating conditions of the nonlinear process; executing the trained nonlinear approximator to determine initial values for the one or more parameters of the dynamic parameterized model based on the current status of the nonlinear process; and initializing the parameterized dynamic model with the determined initial values for the one or more parameters; b) formulate an optimization problem, including specifying an objective function for optimization of the nonlinear process; c) generate a profile of manipulated variables for the nonlinear process over a control horizon in accordance with the specified objective function for optimization of the nonlinear process; d) operate the parametric universal nonlinear dynamic approximator in accordance with the generated profile of manipulated variables, thereby generating predicted outputs for the nonlinear process; e) determine a deviation of the predicted outputs from a desired behavior of the nonlinear process; f) repeat b)- e) one or more times to determine an optimal profile of manipulated variables in accordance with the specified objective function for optimization of the nonlinear process; g) operate the nonlinear process in accordance with the optimal profile of manipulated variables, thereby generating process output; and repeat a)- g) one or more times to dynamically control the nonlinear process. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A non-transitory computer readable memory medium that stores computer executable instructions that when executed by a processor perform training a parametric universal nonlinear dynamic approximator of a nonlinear process, by implementing:
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identifying process inputs and outputs (I/O); determining an order for a parameterized dynamic model comprised in the parametric universal nonlinear dynamic approximator, wherein the order specifies the number of parameters for the parameterized dynamic model, and wherein the parameters of the parameterized dynamic model are not inputs or outputs of the nonlinear process; determining a structure for a nonlinear approximator comprised in the parametric universal nonlinear dynamic approximator for modeling dependencies of the parameters of the parameterized dynamic model upon operating conditions of the nonlinear process; collecting data for the identified process I/O; determining constraints on behavior of the parametric universal nonlinear dynamic approximator from prior knowledge, including one or more constraints for the nonlinear approximator for modeling dependencies of the one or more parameters of the parameterized dynamic model; formulating an optimization problem for training the nonlinear approximator; executing an optimization algorithm to train the nonlinear approximator subject to the determined constraints by solving the optimization problem, thereby determining the dependencies of the parameters of the parameterized dynamic model upon operating conditions of the process, wherein outputs of the nonlinear approximator are not outputs of the nonlinear process; verifying compliance of the parametric universal nonlinear dynamic approximator with the specified constraints; and storing the trained nonlinear approximator and the parameterized dynamic model, wherein the stored nonlinear approximator and the parameterized dynamic model compose a trained parametric universal nonlinear dynamic approximator; wherein the trained parametric universal nonlinear dynamic approximator is usable to optimize and control the nonlinear process. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A computer implemented method for controlling a nonlinear process, the method comprising:
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a) initializing, using a computer, a parametric universal nonlinear dynamic approximator to a current status of the nonlinear process, comprising process inputs and outputs, said initializing comprising; initializing inputs to a nonlinear approximator comprised in the parametric universal nonlinear dynamic approximator, wherein the nonlinear approximator is trained to model dependencies of one or more parameters of a parameterized dynamic model of the nonlinear process comprised in the parametric universal nonlinear dynamic approximator upon operating conditions of the nonlinear process; executing the trained nonlinear approximator to determine initial values for the one or more parameters of the parameterized dynamic model based on the current status of the nonlinear process; and initializing the parameterized dynamic model with the determined initial values for the one or more parameters; b) formulating, using the computer, an optimization problem, including specifying an objective function for optimization of the nonlinear process; c) generating, using the computer, a profile of manipulated variables for the nonlinear process over a control horizon in accordance with the specified objective function for optimization of the nonlinear process; d) operating, using the computer, the parametric universal nonlinear dynamic approximator in accordance with the generated profile of manipulated variables, thereby generating predicted outputs for the nonlinear process; e) determining, using the computer, a deviation of the predicted outputs from a desired behavior of the nonlinear process; f) repeating b)-e) one or more times to determine an optimal profile of manipulated variables in accordance with the specified objective for the nonlinear process; g) operating the nonlinear process in accordance with the optimal profile of manipulated variables, thereby generating process output; and repeating a)-g) one or more times to dynamically control the nonlinear process. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A non-transitory computer readable memory medium that stores computer executable instructions that when executed by a processor perform controlling a nonlinear process, by implementing:
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a) initializing a parametric universal nonlinear dynamic approximator to a current status of the nonlinear process, comprising process inputs and outputs, said initializing comprising; initializing inputs to a nonlinear approximator comprised in the parametric universal nonlinear dynamic approximator, wherein the nonlinear approximator is trained to model dependencies of one or more parameters of a parameterized dynamic model of the nonlinear process comprised in the parametric universal nonlinear dynamic approximator upon operating conditions of the nonlinear process; executing the trained nonlinear approximator to determine initial values for the one or more parameters of the parameterized dynamic model based on the current status of the nonlinear process; and initializing the parameterized dynamic model with the determined initial values for the one or more parameters; b) formulating an optimization problem, including specifying an objective function for optimization of the nonlinear process; c) generating a profile of manipulated variables for the nonlinear process over a control horizon in accordance with the specified objective function for optimization of the nonlinear process; d) operating the parametric universal nonlinear dynamic approximator in accordance with the generated profile of manipulated variables, thereby generating predicted outputs for the nonlinear process; e) determining a deviation of the predicted outputs from a desired behavior of the nonlinear process; f) repeating b)-e) one or more times to determine an optimal profile of manipulated variables in accordance with the specified objective for the nonlinear process; g) operating the nonlinear process in accordance with the optimal profile of manipulated variables, thereby generating process output; and repeating a)-g) one or more times to dynamically control the nonlinear process. - View Dependent Claims (31, 32)
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33. A system for controlling a nonlinear process, the system comprising:
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means for a) initializing a parametric universal nonlinear dynamic approximator to a current status of the nonlinear process, comprising process inputs and outputs, comprising; means for initializing inputs to a nonlinear approximator comprised in the parametric universal nonlinear dynamic approximator, wherein the nonlinear approximator is trained to model dependencies of one or more parameters of a parameterized dynamic model of the nonlinear process comprised in the parametric universal nonlinear dynamic approximator upon operating conditions of the nonlinear process; means for executing the trained nonlinear approximator to determine initial values for the one or more parameters of the parameterized dynamic model based on the current status of the nonlinear process; means for initializing the parameterized dynamic model with the determined initial values for the one or more parameters; means for b) formulating an optimization problem, including specifying an objective function for optimization of the nonlinear process; means for c) generating a profile of manipulated variables for the nonlinear process over a control horizon in accordance with the specified objective function for optimization of the nonlinear process; means for d) operating the parametric universal nonlinear dynamic approximator in accordance with the generated profile of manipulated variables, thereby generating predicted outputs for the nonlinear process; means for e) determining a deviation of the predicted outputs from a desired behavior of the nonlinear process; means for f) repeating b)-e) one or more times to determine an optimal profile of manipulated variables in accordance with the specified objective for the nonlinear process; means for g) operating the nonlinear process in accordance with the optimal profile of manipulated variables, thereby generating process output; and means for repeating a)-g) one or more times to dynamically control the nonlinear process.
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Specification