Experimental results of fractional order PI controller designed for second order plus dead time (SOPDT) processes

The present paper presentes the tuning of a Fractional Order Proportional Integral (FOPI) controller for second-order-plus-time-delay (SOPDT) plants. The tuning procedure is based on imposing frequency domain constraints for the open loop system with the FOPI controller and the SOPDT plant. The gain crossover frequency, phase margin and the iso-damping property that guarantees a certain degree of robustness to gain variations are imposed in order to obtain the parameters of the fractional order controller. The proposed method is validated by real life implementation on a process whose dynamics are approximated to a SOPDT model. The settling time, steady state error, robustness and disturbance rejection capabilities are analyzed using experimental test cases.