Autotuning of a Robust Fractional Order PID Controller

Fractional order PI/PD controllers are generalizations of the well-known PI/PD controllers with an extra parameter usually used to enhance the robustness of the closed loop system. In this paper, an autotuning method, referred to as the fractional order KC autotuner, is presented for tuning fractional order PI/PD controllers. The method is an extension of a previously presented autotuning principle and produces controllers, which are robust to system gain variations. Additionally, the method can also be adapted to obtain robust controllers to time delay, time constant variations, etc. The advantages of this autotuning method reside in the simplicity of the approach: 1) it requires solely one single sine test on the process; 2) it does not need the process model and 3) it eliminates the complex nonlinear equations in the traditional fractional order controller design procedure. Numerical examples are included to validate the method. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.