Robustness versus performance in PDO FPI Control of the IPDT plant

This paper deals with robustness evaluation of the predictive disturbance observer based filtered PI (PDO FPI) control. Robust performance of loops with integral plants, different order filters and with an uncertain dead time is examined by the performance portrait method. The analysis does not confirm the up to now accepted view that the best robustness corresponds to the 1st order filters. Features of robust performance measures in the time domain are discussed.