Method for control of a plant

• US 6,745,087 B2
• Filed: 12/14/2000
• Issued: 06/01/2004
• Est. Priority Date: 01/08/1999
• Status: Expired due to Fees

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Shah, Sunil C.
• Primary Examiner(s): PATEL, RAMESH B
• Application Number:
  US09/737,992
• Publication Number:
  US 20010014834A1
• Time in Patent Office: 1,265 Days
• Field of Search: 700/29-33, 700/2-5, 700/8-10, 700/18-20, 700/83, 700/86, 700/87, 700/88, 700/97, 700/98, 700/108-110, 700/119, 700/65-66, 702/57, 702/85, 702/182, 702/183, 702/181, 702/188
• US Class Current: 700/29
• 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
• CPC Class Codes: G11B 20/00 Signal processing not specific to the method of recording or reproducing; Circuits therefor

Abstract

A scheme for management of uncertainty in control systems that require adaptation is described. The scheme removes as much uncertainty as possible at design time and manufacturing time by taking advantage of available computer resources in pre-computing a large set of robustness-performance tradeoffs. a plant that is controlled by having model controllers and a data evaluator receive monitored signals. The monitored signals are evaluated to determine when sufficient information is received. One of the model controllers generates a control signal based upon the monitored signals received.

Claims

1. A method of controlling a plant, comprising:

receiving a plurality of monitored signals by a plurality of model controllers and a data evaluator;

evaluating the plurality of monitored signals to determine when sufficient information of the plurality of monitored signals is received;

selecting a model controller of the plurality of model controllers to generate a control signal based on the plurality of monitored signals; and

using the model controller to provide the control signal to the plant.

2. The method of claim 1, wherein each of the plurality of the model controllers have adaptive parameters affecting the generated control signal and wherein the method further comprises gradually adjusting the adaptive parameters of the selected one of the plurality of model controllers.

3. The method of claim 1, wherein evaluating comprises performing a generalized likelihood ratio test on the plurality of monitored signals to determine which of the plurality of model controllers to select.

4. The method of claim 1, wherein a default model controller is selected to generate the control signal when insufficient information of the plurality of signals is received.

5. The method of claim 1, wherein a fall-back model controller is selected to generate the control signal when insufficient information of the plurality of signals is received, the fall-back model controller designed to be robust enough to maintain the plant until sufficient information of the plurality of monitored signals is received.

6. The method of claim 1, wherein the data evaluator includes a model hypothesis tester and test confidence indicator.

7. A controller, the controller comprising:

means for receiving a plurality of monitored signals by a plurality of model controllers and a data evaluator;

means for evaluating the plurality of monitored signals to determine when sufficient information of the plurality of monitored signals is received;

means for selecting one of the plurality of model controllers to generate a control signal based on the plurality of monitored signals; and

means for using the model controller to provide the control signal to the plant.

8. The controller of claim 7, wherein each of the model controllers have adaptive parameters affecting the generated control signal and wherein the apparatus further comprises means for gradually adjusting the adaptive parameters of the selected one of the plurality of model controllers.

9. The controller of claim 7, wherein the means for evaluating comprises means for performing a generalized likelihood ratio test on the plurality of monitored signals to determine which of the plurality of model controllers to select.

10. The controller of claim 7, further comprising means to generate the control signal when insufficient information of the plurality of signals is received.