ROBUST CONTROLLER TUNING BASED ON COEFFICIENT DIAGRAM METHOD

In this paper, Coefficient Diagram Method (CDM), which is a controller design method that provides remarkable time-domain characteristics, is combined with a PI controller in order to design robust controllers. In particular, it has been demonstrated that it is possible to provide robust tuning rules for first order plus time delay (FOPTD) systems. Here, PI controller is used for improving the steady-state response of the system and for providing an extra parameter for tuning robustness. Pole Colouring method is used for measuring robustness. Calculation of robust tuning rules is computationally expensive, since it is required to find the best values of the free parameter of the PI controller for different plants. However, after using a curve fitting algorithm it is possible to obtain simple tuning rules to determine robust controllers.