Pareto-based polynomial tuning rule for 2DoF PID controllers for time-delayed dominant processes with robustness consideration

A novel polynomial tuning rule is proposed for second order plus time delay system where the time delay is dominant with respect to the time constant. The controller used is a two degrees of freedom PID controller. The rule was found by a curve fitting procedure over data obtained from a series of Pareto optimization with the robustness of the controlled system as constraint. It was found that the proposed methodology is versatile in the sense that, the control engineer is able to choose the allowed degradation of the performance of the system from three different sources of disturbances (set-point changes, input disturbances and output disturbances). The method is compared to the uSORT2 tuning, showing excellent performance results.