Robustness analysis of a disturbance-observer based PI control

This paper deals with a robustness analysis of a disturbance observer (DO) based filtered PI control (DO-FPI) for integral first order plants based on the performance portrait method. For the loop robustification and a noise attenuation the loop is augmented by n-th order filters used in the inner DO loop, as well as in the outer loop with the stabilizing P controller. Although the derived results may be used in a broad range of tasks originating in a control of plants with a dominant first order dynamics, for the sake of simplicity they focus on control of a single integrator.