Fractional order PID controller with online tuning based on FRIT and RLS

Abstract

This paper presents a new strategy for online robust control-based fractional order PID controller (FPID). The technique suggests an online parameters tuning of the FPID using fictitious reference iterative tuning (FRIT) approach. This approach enables us to track the desired optimal FPID parameters online using experimental data without any plant model identification. After having set the optimal non-integer orders α and β, the gains of the FPID are then estimated in a recursive manner using the so-called recursive least squares (RLSs) algorithm with forgetting factor, which can cope with variation of plant characteristics adaptively. The performances of this technique are compared with other results already existing in the literature through some typical examples; the results of the proposed approach show significant performance improvement.