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Process control method and control system

  • US 5,025,499 A
  • Filed: 04/12/1989
  • Issued: 06/18/1991
  • Est. Priority Date: 04/13/1988
  • Status: Expired due to Term
First Claim
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1. A process control system for controlling a process, comprising:

  • differentiation means for receiving different kinds of process information from process sensors which measure different variables of a process and calculating amounts of change of said process information with respect to time;

    qualitative evaluation means, connected to said differentiation means, for evaluating in evaluation stages said process information or said amounts of change of said process information with respect to time by a membership function previously determined as having fuzzy amounts;

    qualitative inference means, connected to said qualitative evaluation means, for inferring a qualitative evaluation value set of control target process information after a unit of time by experiential rules on the basis of combinations of values in each of said evaluation stages;

    centroid arithmetic means, connected to said qualitative inference means, for receiving said qualitative evaluation value set inferred by said qualitative inference means and determining an amount of control of said control target process information by centroid arithmetic processing of said membership function; and

    output means, connected to said centroid arithmetic means, for supplying said amount of control determined by said centroid arithmetic means to said process, thereby causing a change in operation of said process according to said amount of control.

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