Interactive tools for designing fractional-order PID controllers

In this paper, we present two Sysquake interactive tools for the design of fractional-order proportional-integral-derivative (FOPID) controllers. The first tool deals with the time and frequency domain design of FOPID controllers, allowing the user to analyze the effects of changing user-chosen parameters. In the time domain, both set-point and load disturbance step responses of the control system are shown, as well as the effect of measurement noise. In the frequency domain, the Bode diagrams of all the most important closed-loop transfer functions are plotted. The second tool allows the user to determine automatically the controller parameters by applying a loop shaping technique, namely, by mapping a point of the process Nyquist plot to a target point of the loop transfer function Nyquist plot with a predened value of its derivative. In this context, constraints on the gain or phase margin or on the maximum sensitivity can be effectively considered. It is believed that this kind of Computer Aided Control System Design tools are very useful from an educational viewpoint and in allowing a widespread use of FOPID controllers in industry.