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Method and automatic control apparatus for controlling a technological process

  • US 4,545,008 A
  • Filed: 12/14/1982
  • Issued: 10/01/1985
  • Est. Priority Date: 04/20/1981
  • Status: Expired due to Fees
First Claim
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1. A method utilizing an automatic control system for controlling a technological process by maintaining an output paramater of said process at a predetermined level with an automatic controller of the system susceptible of parameter variations in opposed directions in one of which the stability margin of the automatic control system is decreased, wherein for optimizing control quality as a function of said variations of said parameter of the controller said method comprises gradually changing the parameter of the automatic controller;

  • determining the change and direction of change of an index of control quality with said changing parameter;

    reversing the direction of change of said parameter of the automatic controller if said index of control quality continues to change in the direction of decrease in control quality for a predetermined time;

    determining the value of the index of control quality during variation of the index of control quality from increasing to decreasing control quality;

    storing the value of said index of control quality thus determined at one of the instants of change in the direction of variation of said index of control quality from said increasing to decreasing control quality;

    storing a new value of said index of control quality at the instant of the first change in the direction of variation of said index of control quality from said increasing to decreasing control quality when the deviation of the determined value of said index of control quality from the last previously stored value exceeds a predetermined value;

    the improvement being characterized by increasing the speed of parameter variation of the controller in a direction corresponding to improved control quality, should said parameter be changing in a direction of decrease in the stability margin of the automatic control system while said index of control quality is changing in a direction of increase in control quality;

    said improvement comprising(a) abruptly changing said parameter of the automatic controller is from a predetermined value corresponding to a stable state of the control system, to a value corresponding to an unstable state of the control system during the time between the instant at which the deviation of the determined value of said parameter of the controller, from the latest stored value, exceeds said predetermined value of deviation and the instant of storing the next value of said index of control quality;

    (b) abruptly changing, after a time less than that at which said automatic control system may lose stability, said controller parameter to a value corresponding to a greater stability margin of the control system than said predetermined value of the parameter; and

    (c) gradually changing said controller parameter in direction of decrease in the stability margin of the automatic control system until said controller parameter again attains said predetermined value or the direction of variation of said index of control quality changes from increasing to decreasing control quality.

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