Controllers that determine optimal tuning parameters for use in process control systems and methods of operating the same

• US 6,253,113 B1
• Filed: 08/20/1998
• Issued: 06/26/2001
• Est. Priority Date: 08/20/1998
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Lu, Z. Joseph
• Primary Examiner(s): Beausoleil, Robert
• Assistant Examiner(s): VO, TIM T
• Application Number:
  US09/137,358
• Time in Patent Office: 1,041 Days
• Field of Search: 700/29, 700/36, 700/30, 700/31, 700/44, 700/45, 700/37, 700/32, 700/33, 700/34, 700/28
• US Class Current: 700/28
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05B 13/042 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 5/01 electric

Abstract

The present invention provides a processing system that is capable of achieving substantially optimal control performance of a process facility on a “worst case” process system by accounting for changing system dynamics. The processing system includes a storage device and a processor. The storage device is operable to represent (i) at least one of a plurality of associated processes mathematically to define the various relationships among different inputs and outputs of the one or more represented associated processes, and (ii) uncertainty factors that are associated with these defined relationships. The uncertainty factors define a range of dynamics across which the one or more represented associated processes operate, an error in the mathematical representation, or, alternatively, some combination of the same. The processor is responsive to the mathematical representation and the uncertainty factors and is capable of determining tuning parameters for use by the control system to control the one or more represented associated processes and thereby cooperate to optimize said process facility.

Claims

1. A processing system for use with a control system that controls associated processes of a process facility, comprising:

a storage device that is operable to represent (i) at least one of said associated processes mathematically, said mathematical representation defining relationships among inputs and outputs of said at least one of said associated processes, and (ii) uncertainty factors that are associated with said defined relationships, said uncertainty factors defining at least one of a range of dynamics across which said at least one of said associated processes operates and an error in said mathematical representation; and

a processor that is capable of determining, in response to said mathematical representation and said uncertainty factors, tuning parameters for use by said control system to control said at least one of said associated processes and thereby cooperate to optimize said process facility.

2. The processing system set forth in claim 1 wherein said storage device is further operable to represent common plant occurrences from a group consisting of changes in process throughput, feed stock quality, seasonal temperature, and equipment status.

3. The processing system set forth in claim 1 wherein said uncertainty factors are associated with an objective function, J, wherein J=f(k_c, τ

_i, τ

_d, τ

_f, Model(p)).

4. The processing system set forth in claim 1 wherein said uncertainty factors are associated with at least one of a proportional constant, an integral constant, a derivative constant, and a filter constant.

5. The processing system set forth in claim 2 wherein said processor determines said tuning parameters in response to said common plant occurrences.

6. The processing system set forth in claim 3 wherein said Model(p) is selected from a group consisting of Laplace, ARX, FIR, Step-Response.

7. The processing system set forth in claim 1 wherein said uncertainty factors are associated with an objective function, J, wherein J=f(k_c, τ

_i, τ

_d, τ

_f, Model(p)).

8. A method of operating a processing system for use with a control system that controls associated processes of a process facility, comprising the step of:

representing in a storage device (i) at least one of said associated processes mathematically, said mathematical representation defining relationships among inputs and outputs of said at least one of said associated processes, and (ii) uncertainty factors that are associated with said defined relationships, said uncertainty factors defining at least one of a range of dynamics across which said at least one of said associated processes operates and an error in said mathematical representation; and

determining with a processor, in response to said mathematical representation and said uncertainty factors, tuning parameters for use by said control system to control said at least one of said associated processes and thereby cooperate to optimize said process facility.

9. The method of operating a process control system set forth in claim 8 further comprising the step of representing in said storage device common plant occurrences selected from a group consisting of changes in process throughput, feed stock quality, seasonal temperature, and equipment status.

10. The method of operating a process control system set forth in claim 8 wherein said uncertainty factors are associated with an objective function, J, wherein J=f(k_c, τ

_i, τ

_d, τ

_f, Model(p)).

11. The method of operating a process control system set forth in claim 8 wherein said uncertainty factors are associated with at least one of a proportional constant, an integral constant, a derivative constant, and a filter constant.

12. The method of operating a process control system set forth in claim 8 wherein said uncertainty factors are associated with an objective function, J, wherein J=f(k_c, τ

_i, τ

_d, τ

_f, Model(p)).

13. The method of operating a process control system set forth in claim 9 further comprising the step of determining said tuning parameters with said processor in response to said common plant occurrences.

14. The method of operating a process control system set forth in claim 10 wherein said Model(p) is selected from a group consisting of Laplace, ARX, FIR, Step-Response.

15. A processing system for use with a control system that controls associated processes of a process facility, comprising:

a storage device that is operable to represent (i) at least one of said associated processes mathematically, said mathematical representation defining relationships among inputs and outputs of said at least one of said associated processes, and (ii) uncertainty factors that are associated with said defined relationships, said uncertainty factors defining at least one of a range of dynamics across which said at least one of said associated processes operates and an error in said mathematical representation, and said uncertainty factors are associated with at least one of a proportional constant, an integral constant, a derivative constant, and a filter constant; and

a processor that is capable of determining, in response to said mathematical representation and said uncertainty factors, tuning parameters for use by said control system to control said at least one of said associated processes and thereby cooperate to optimize said process facility.

16. The processing system set forth in claim 15 wherein said storage device is further operable to represent common plant occurrences from a group consisting of changes in process throughput, feed stock quality, seasonal temperature, and equipment status.

17. The processing system set forth in claim 15 wherein said uncertainty factors are associated with an objective function, J, wherein J=f(k_c, τ

_i, τ

_d, τ

_f, Model(p)).

18. The processing system set forth in claim 15 wherein said uncertainty factors are associated with an objective function, J, wherein J=f(k_c, τ

_i, τ

_d, τ

_f, Model(p)).

19. The processing system set forth in claim 16 wherein said processor determines said tuning parameters in response to said common plant occurrences.

20. The processing system set forth in claim 17 wherein said Model (p) is selected from a group consisting of Laplace, ARX, FIR, Step-Response.