Fuzzy Logic Based Tuning of PID Controllers for Plants with Under-Damped Response

Abstract In this paper a novel methodology, based on fuzzy logic, for the tuning of Proportional-Integral-Derivative (PID) controllers applied to plants with under-damped response is proposed. Specifically, starting from the well-known Ziegler-Nichols tuning formula, the parameters of the controller are modified in a one-step procedure in order to improve the step response of the overall system. The scaling coefficients are determined using fuzzy inference systems in which the inputs are the estimated dead time, natural frequency and relative damping of the plant and no particular computational extra-effort is required to implement the method. Simulation results show that the technique is effective in providing high performances in the step response of different systems.