Robust PID Controller Design for Performance Based on Ultimate Plant Parameters

The paper deals with a new robust PID controller design method based on integrating requirements on transient performance into the popular frequency-domain Ziegler-Nichols design approach. The developed method provides support to the designer by converting identified ultimate plant parameters into PID controller parameters using variable weights that depend on expected maximum overshoot ηmax and settling time ts of the closed-loop step response. An extension of this method is proposed which enables to design PID controller guaranteeing robust stability and nominal performance for the uncertain plant modeled using unstructured uncertainty. Fulfillment of performance specification is guaranteed for the nominal model as well as for the worst-case one. The main advantage of the proposed method is a direct integration of performance requirements in the design procedure. Effectiveness of the proposed robust PID design method is verified by simulations and experiments on the real plant.