PIIσ_FD CONTROLLER FOR LINEAR TIME INVARIANT SINGLE INPUT/SINGLE OUTPUT SYSTEMS

Saleh M. Radaideh - Mohammed T. Hayajneh - Issam A. Smadi

   The aim of this paper is to auto tune the length of the integration interval, σ, of the PII_σ D controller in such a manner as to increase its accuracy using the fuzzy theory which generalizes 0 and 1 membership values of a crisp set to a membership function of a fuzzy sets which are classes with an un-sharp boundary. In other words, the length of integration in the proposed controller is a function of the error signal, and computed using a fuzzy logic controller. The modified controller will be denoted as PIIσ_FD, which is a modification for PII_σD controller. In order to test the effectiveness of the proposed controller and to compare the performance of the proposed controller with PID and PII_σD controllers, numerical examples are presented. Using Ziegler-Nichols tuning rules, all simulation results prove that the performance of the PIIσ_FD controller is better than the performance of the others.

Keywords: fuzzy logic controller, PID, PII_σD, Ziegler-Nichols, fuzzification, defuzzification

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