Method and apparatus for determining the sensitivity of inputs to a neural network on output parameters
DCFirst Claim
1. A system for determining a set of sensitive inputs in a non-linear predictive network having stored therein a representation of a plant, comprising:
- a configurable network having;
an input layer for receiving a defined number of input variables, which defined number of input variables is a variable number,an output layer for outputting a defined number of outputs, each associated with an output variable, anda hidden layer for mapping said input layer to said output layer through a stored learned representation of the plant;
a dataset of training patterns representing substantially all of the input variables to the plant and associated measured output variables of the plant, with each of said training patterns having input values associated with said input variables and corresponding output values associated with said output variables;
a training system for training said configurable network in accordance with a predetermined training algorithm;
a sensitivity processor for determining as a sensitivity value the effect of each of said input variables input to said configurable network on a learned representation of said output variables, wherein the combined effects of all other input variables are taken into account;
a central processor for configuring said network to receive substantially all of said input variables in a first mode and controlling said training system to train said configurable network with substantially all of said input variables and said output variables in said dataset;
said central processor controlling said sensitivity processor to determine said sensitivity values associated with each of said input variables and compare said determined sensitivity values with a predetermined threshold and select only the ones of said input variables from said dataset having a sensitivity value that exceeds said sensitivity threshold, this being defined as a selected dataset; and
said central processor operable to configure said network to receive only input variables from said received input variables from said selected dataset and control said training system to train said configurable network on said selected dataset to provide a stored learned representation of a plant trained only on the selected input variables.
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Abstract
A distributed control system (14) receives on the input thereof the control inputs and then outputs control signals to a plant (10) for the operation thereof. The measured variables of the plant and the control inputs are input to a predictive model (34) that operates in conjunction with an inverse model (36) to generate predicted control inputs. The predicted control inputs are processed through a filter (46) to apply hard constraints and sensitivity modifiers, the values of which are received from a control parameter block (22). During operation, the sensitivity of output variables on various input variables is determined. This information can be displayed and then the user allowed to select which of the input variables constitute the most sensitive input variables. These can then be utilized with a control network (470) to modify the predicted values of the input variables. Additionally, a neural network (406) can be trained on only the selected input variables that are determined to be the most sensitive. In this operation, the network is first configured and trained with all input nodes and with all training data. This provides a learned representation of the output wherein the combined effects of all other input variables are taken into account in the determination of the effect of each of the input variables thereon. The network (406) is then reconfigured with only the selected inputs and then the network (406) again trained on only the input/output pairs associated with the select input variables.
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Citations
20 Claims
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1. A system for determining a set of sensitive inputs in a non-linear predictive network having stored therein a representation of a plant, comprising:
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a configurable network having; an input layer for receiving a defined number of input variables, which defined number of input variables is a variable number, an output layer for outputting a defined number of outputs, each associated with an output variable, and a hidden layer for mapping said input layer to said output layer through a stored learned representation of the plant; a dataset of training patterns representing substantially all of the input variables to the plant and associated measured output variables of the plant, with each of said training patterns having input values associated with said input variables and corresponding output values associated with said output variables; a training system for training said configurable network in accordance with a predetermined training algorithm; a sensitivity processor for determining as a sensitivity value the effect of each of said input variables input to said configurable network on a learned representation of said output variables, wherein the combined effects of all other input variables are taken into account; a central processor for configuring said network to receive substantially all of said input variables in a first mode and controlling said training system to train said configurable network with substantially all of said input variables and said output variables in said dataset; said central processor controlling said sensitivity processor to determine said sensitivity values associated with each of said input variables and compare said determined sensitivity values with a predetermined threshold and select only the ones of said input variables from said dataset having a sensitivity value that exceeds said sensitivity threshold, this being defined as a selected dataset; and said central processor operable to configure said network to receive only input variables from said received input variables from said selected dataset and control said training system to train said configurable network on said selected dataset to provide a stored learned representation of a plant trained only on the selected input variables. - View Dependent Claims (2)
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3. A control network for predicting control inputs for input to a distributed control system, which distributed control system outputs controls for input to a plant, the control inputs associated with the input variables to the plant, comprising:
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a control model for storing a representation of the plant; a desired value input defining desired operating parameters for the plant; said control model operable to receive as inputs the control inputs output by the distributed control system and said desired value input, and predicted control input values for input as updated control inputs to the distributive distributed control system that are necessary to achieve said desired operating parameters associated with said desired value input; a memory for storing sensitivity modifiers for defining the effect of each of the input variables on the plant output; and a modifier circuit for modifying the value of the predicted control input values prior to input to the distributed control system in accordance with a predetermined function of said pre-stored sensitivity modifiers in said memory. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for generating control inputs with a distributed control system that generates control inputs for a plant, comprising the steps of:
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providing a control model that contains a representation of a plant; inputting a desired input value that defines desired operating parameters for the plant; inputting the control inputs generated by the distributed control system to the control model; predicting control input values that will allow the plant to operate at the desired input value by processing the desired input value and current control inputs from the distributed control system to generate an error and minimizing the error with the control model, the predicted control inputs operable to be input to the distributed control system in order for the distributed control system generate new control inputs; storing sensitivity modifiers for defining the effect of each of the input variables on the plant output; and modifying the value of the predicted control input values prior to input to the distributed control system in accordance with a predetermined function of the stored sensitivity modifiers. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification