Tuning of robust FO[PI] plus fractional lead controller for integrating time-delay systems

This paper presents the design of a robust fractional-order controller consisting of FO[PI] controller and fractional lead compensator, for the generalised, known and minimum-phase integrating time-delay plants. The fractional-order controller is designed to satisfy design specifications of phase margin, gain crossover frequency and flat phase constraint. Using Bode's integral relationship, a FO[PI] controller is designed to satisfy the flat phase constraint which ensure that phase bode plot of the compensated system is flat at gain crossover frequency. Then, the design of fractional lead compensator is done to satisfy design specifications of phase margin and gain crossover frequency. The simulation results illustrate the effectiveness and simplicity of presented method for robust controller design with an iso-damping property.