Control system using process model

• US 20030045962A1
• Filed: 08/30/2001
• Published: 03/06/2003
• Est. Priority Date: 08/30/2001
• Status: Active Grant

• Current Assignee: Fisher-Rosemount Systems Incorporated (Emerson Electric Company)
• Original Assignee: Fisher-Rosemount Systems Incorporated (Emerson Electric Company)
• Inventors: Eryurek, Evren, Kavaklioglu, Kadir
• Granted Patent: US 6,772,036 B2
• Time in Patent Office: Days
• US Class Current: 700/128
• CPC Class Codes: D21G 9/0027 controlling the forming section
• CPC Class Codes: D21H 23/78 Controlling or regulating not limited to any particular process or apparatus
• CPC Class Codes: G05B 13/029 using neural networks and expert systems
• CPC Class Codes: G05B 13/042 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 17/02 electric

Abstract

A control system is provided for controlling a process for making paper or paper pulp. The process has a process product output at an end of the process. The controls include a process variable sensor input configured to receive a process variable related to the process. The controller is configured to provide a control signal to control the process. A process model has a model product output which is a model representation of the process product output. The model process output is a function of the sensed process variable and a product output setpoint representative of a desired process product output. The control signal is a function of the product output setpoint and the modeled product output.

Claims

1. A control system for controlling a process for making paper or paper pulp having a process product output at an end of the process, comprising:

a process variable sensor input configured to receive a process variable related to the process for making paper or pulp paper sensed by a process variable sensor which provides a process variable output;

a control element output configured to provide a control signal to a control element which controls the process in response to the control signal;

a process model having model product output which is a model representation of the process product output in response to the sensed process variable;

a product output setpoint representative of a desired process product output; and

a controller configured to compare the product output setpoint to the modeled product output and responsively provide the control signal to the control element.

2. The control system of claim 1 wherein the process product output is controlled to achieve a desired product quality.

3. The control system of claim 1 including a plurality of process variable sensors and wherein the model product output is a function of process variable outputs from the plurality of process variable sensors.

4. The control system of claim 1 wherein the model comprises a plurality of rules which model the process.

5. The control system of claim 1 wherein the model comprises a neural network which models the process.

6. The control system of claim 1 wherein the model comprises fuzzy logic which models the process.

7. The control system of claim 1 wherein the process variable sensor is in a first control loop, the control element is in a second control loop which is down stream from the first loop, and wherein the controller corrects for process variations in the first control loop by adjusting the control element to achieve a desired product quality in the process product output.

8. The control system of claim 1 wherein the controller provides feed forward control as a function of the model product output.

9. The control system of claim 1 wherein the model is implemented in a microprocessor based system.

10. The control system of claim 1 wherein the model is implemented in a process device in physical proximity to the process variable sensor.

11. The control system of claim 1 wherein the process variable sensor transmits sensed process variables over a two wire process control loop.

12. The control system of claim 1 wherein the process model is coupled to the process variable sensor over a control loop which operates in accordance with Fieldbus.

13. The control system of claim 1 wherein the model is a function of an observed process history.

14. A method for controlling a process for making paper or paper pulp, the process of the type having a process product output at the end of the process, comprising:

obtaining a process variable related to the process;

modeling the process product output as a function of at least the obtained process variable;

obtaining a setpoint related to a desired process product output; and

generating a control signal as a function of the modeled process product output and the setpoint.

15. The method of claim 14 wherein the process product output is controlled to achieve a desired product quality.

16. The method of claim 14 wherein the modeling is based upon a plurality of process variables.

17. The method of claim 14 wherein the modeling is based upon a plurality of rules.

18. The method of claim 14 wherein the modeling is based upon a neural network.

19. The method of claim 14 wherein the modeling is based upon fuzzy logic.

20. The method of claim 14 wherein the control signal is generated to correct for potential future deviations in the process product output.

21. The method of claim 14 wherein the modeling is a function of an observed process history.

22. The method of claim 14 wherein obtaining a process variable comprises receiving a process variable from a two-wire process control loop.