Robust Proportional-Integral Control of a Laboratory Model Using Programmable Logic Controller SIMATIC S7-300

The main aim of the contribution is to present a possible approach to design of simple Proportional-Integral (PI) robust controllers and subsequently to demonstrate their applicability during control of a laboratory model with uncertain parameters through the Programmable Logic Controller (PLC) SIMATIC S7–300 by Siemens Company. The proposed and utilized synthesis consists of two steps – the former one is a determination of controller parameters area, which ensures the robustly stable control loop and which is based on the computing/plotting the stability boundary locus while the latter one lies in the final choice of the controller itself relying on algebraic techniques. The basic theoretical parts are followed by laboratory experiments in which the 3rd order nonlinear electronic model has been successfully controlled in various working points.