Ultimate Data Based Robust PID Design for Performance

A novel PID tuning method is presented to achieve prescribed performance (in terms of maximum overshoot and settling time) for uncertain systems with unstructured uncertainties. In the first step of the design procedure the plant is identified using a harmonic excitation signal with frequency ©n. In the second step, two recently developed PID controller design approaches are applicable: 1. the approach based on guaranteed phase margin ϕM suitable for systems without integral behaviour and with/without time delay, and for systems with integral behaviour; 2. the approach based on guaranteed gain margin GM, suitable for systems without integral behaviours with unstable zero. Both approaches are based on shifting a selected point of the frequency response of the unknown system into the gain crossover frequency (if using the HM approach) or the phase crossover frequency (if using the GM approach). The developed algorithm has been extended to robust PID controller design for plants with unstructured uncertainties.