Leeds & Northrup Company

Paul Anderson

Samuel A Arcara

A P-I-D controller in a process control system is self tuned in response to discrete time model identification parameters which are converted to P-I-D form. Additionally, the P-I-D parameters are limited to prevent them from exceeding the controller's specified range.

Self tuning of P-I-D controller by conversion of discrete time model

A process for automatically identifying the parameters of a controller which controls a process and a process model which includes changing alternately the set point for the process by a predetermined value above and below the desired set point of the process which is continued until the parameters of the process model describe the process. The apparatus includes means for creating a cycle that has a plurality of steps, means for comparing a proportional amount of a set point change with a corresponding value of the process during one of the cycles steps during which the parameters are identified, means for repeating the cycle until the change in the values of the parameters between adjacent cycle is less than a predetermined amount, and means for terminating the cycle repetition if the parameter change between adjacent cycles is less than the predetermined amount.

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Green Lane, PA, United States of America

Paul Anderson