Method and apparatus for controlling a non-linear mill

• US 6,493,596 B1
• Filed: 02/28/2000
• Issued: 12/10/2002
• Est. Priority Date: 05/06/1996
• Status: Expired due to Term

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Pavilion Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Martin, Gregory D., Keller, James David, Piche, Stephen, Boe, Eugene, Havener, John P., Gerules, Mark, Timmer, Douglas
• Primary Examiner(s): Black, Thomas
• Assistant Examiner(s): GAIN, EDWARD F
• Application Number:
  US09/514,733
• Time in Patent Office: 1,016 Days
• Field of Search: 700/37, 700/32, 700/40, 700/31, 700/30, 700/29, 700/28, 700/47
• US Class Current: 700/37
• CPC Class Codes: G05B 13/042 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 13/048 using a predictor
• CPC Class Codes: G05B 17/02 electric

Abstract

A method and apparatus for controlling a non-linear mill. A linear controller is provided having a linear gain k that is operable to receive inputs representing measured variables of the plant and predict on an output of the linear controller predicted control values for manipulatible variables that control the plant. A non-linear model of the plant is provided for storing a representation of the plant over a trained region of the operating input space and having a steady-state gain K associated therewith. The gain k of the linear model is adjusted with the gain K of the non-linear model in accordance with a predetermined relationship as the measured variables change the operating region of the input space at which the linear controller is predicting the values for the manipulatible variables. The predicted manipulatible variables are then output after the step of adjusting the gain k.

Claims

1. A method for controlling a non-linear plant, comprising the steps of:

providing a linear controller having a linear gain k that is operable to receive inputs representing measured variables of the plant and predicting on an output of the linear controller predicted control values for manipulatible variables that control the plant;

providing a non-linear model of the plant for storing a representation of the plant over a trained region of the operating input space and having a steady-state gain K associated therewith;

adjusting the gain k of the linear controller with the gain K of the non-linear model in accordance with a predetermined relationship as the measured variables change the operating region of the input space at which the linear controller is predicting the values for the manipulatible variables; and

outputting the predictive manipulatible variables after the step of adjusting the gain k.

2. The method of claim 1, wherein the linear controller is operable to model the dynamics of the plant.

3. The method of claim 1, wherein the dynamics of the plant are modeled over a defined region of the input space.

4. The method of claim 1, wherein the training region of the operating input space over which the non-linear model is representative of the operation of the plant represents a space greater than that over which the linear controller is valid.

5. The method of claim 1, and further comprising the step of controlling the operation of the plant with the predicted control variables after the step of adjusting.