Model-free PID Controller Autotuning Algorithm Based on Frequency Response Analysis

PID controllers are the most popular group of controllers in practical applications. Many theoretical techniques and procedures have been developed for PID controllers with the aim to optimize the function of the control circuits. However, these techniques are seldom applied, except in cases where there are some extreme requirements for the safety and the operational quality of the control loops. Even autotuning of controllers, which some producers have been offering for a quite long time, is not exploited as it might be. There are several reasons for this unsatisfactory state of affairs, one of which is the necessity to master a difficult theoretical background, often requiring perfect models of the dynamics of the controlled process. In this paper, using a laboratory set-up in model representation and also in physical representation, we will discuss some of these reasons in a confrontation with the new idea of performing controller autotuning without knowledge of the controlled plant model.