Non-linear dynamic predictive device
First Claim
1. A predictive device for modeling a non-linear, causal, multiple-input single-output system or process, comprising:
- a plurality of preprocessing units for receiving a working signal including control data inputs, the preprocessing units normalizing the control data inputs, resulting in preprocessed inputs;
a plurality of delay units coupled to the preprocessing units, the delay units time aligning the preprocessed inputs, resulting in time aligned inputs;
a plurality of filter units coupled to the delay units, the filter units being of a substantially simplified configuration as compared to a configuration based upon discrete state space equations, the filter units filtering the time aligned inputs at least according to time, resulting in filtered states;
a non-linear approximator coupled to the filter units and accepting the filtered states, the non-linear approximator generating a single approximator output;
a postprocessing unit coupled to the non-linear approximator to receive the generated approximator output, the postprocessing unit converting the single approximator output to a single device output that represents a prediction of the output of the multiple-input single-output dynamic system being modeled by the device, and wherein the predictive device operates in a plurality of selectable modes including a configuration mode and multiple runtime modes that provide a generalized modeling of non-linear dynamic processes.
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Abstract
A non-linear dynamic predictive device (60) is disclosed which operates either in a configuration mode or in one of three runtime modes: prediction mode, horizon mode, or reverse horizon mode. An external device controller (50) sets the mode and determines the data source and the frequency of data. In the forward modes (prediction and horizon), the data are passed to a series of preprocessing units (20) which convert each input variable (18) from engineering units to normalized units. Each preprocessing unit feeds a delay unit (22) that time-aligns the input to take into account dead time effects. The output of each delay unit is passed to a dynamic filter unit (24). Each dynamic filter unit internally utilizes one or more feedback paths that provide representations of the dynamic information in the process. The outputs (28) of the dynamic filter units are passed to a non-linear approximator (26) which outputs a value in normalized units. The output of the approximator is passed to a post-processing unit (32) that converts the output to engineering units. This output represents a prediction of the output of the modeled process. In reverse horizon mode, data is passed through the device in a reverse flow to produce a set of outputs (64) at the input of the predictive device. These are returned to the device controller through path (66). The purpose of the reverse horizon mode is to provide information for process control and optimization. The predictive device approximates a large class of non-linear dynamic processes. The structure of the predictive device allows it to be incorporated into a practical multivariable non-linear Model Predictive Control scheme, or used to estimate process properties.
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Citations
25 Claims
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1. A predictive device for modeling a non-linear, causal, multiple-input single-output system or process, comprising:
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a plurality of preprocessing units for receiving a working signal including control data inputs, the preprocessing units normalizing the control data inputs, resulting in preprocessed inputs;
a plurality of delay units coupled to the preprocessing units, the delay units time aligning the preprocessed inputs, resulting in time aligned inputs;
a plurality of filter units coupled to the delay units, the filter units being of a substantially simplified configuration as compared to a configuration based upon discrete state space equations, the filter units filtering the time aligned inputs at least according to time, resulting in filtered states;
a non-linear approximator coupled to the filter units and accepting the filtered states, the non-linear approximator generating a single approximator output;
a postprocessing unit coupled to the non-linear approximator to receive the generated approximator output, the postprocessing unit converting the single approximator output to a single device output that represents a prediction of the output of the multiple-input single-output dynamic system being modeled by the device, and wherein the predictive device operates in a plurality of selectable modes including a configuration mode and multiple runtime modes that provide a generalized modeling of non-linear dynamic processes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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15. A computer method for modeling a non-linear, causal, multiple-input single-output, system or process, comprising the steps of:
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(a) receiving and normalizing a working signal including control data inputs, resulting in preprocessed inputs;
(b) aligning the preprocessed inputs, resulting in time aligned inputs;
(c) using a plurality of filter units, filtering the time aligned inputs, at least according to time, resulting in filtered states;
(d) employing a non-linear approximator, generating an approximator output based upon the filtered states; and
(e) converting the approximator output to a model output that represents a prediction of the output of the multiple-input single-output dynamic system being modeled by the method, in a manner that provides a general modeling of non-linear dynamic processes.
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Specification