Designing low-pass filter in equivalent-input-disturbance compensator for improving disturbance-rejection performance

This paper presents a high-order low-pass filter for the equivalent-input-disturbance (EID) approach to improving the disturbance-rejection performance. The configuration characteristic of the presented filter clearly explains the reason why the disturbance-rejection performance is improved and provides a guideline to design it. Using the presented filter to replace the conventional filter derives a high-order EID (HEID) approach. It is easy to apply the small-gain theorem in deriving stability conditions of the HEID-based control system. Moreover, the presented filter is proved to be better than the conventional one. Finally, a comparison shows the validity and superiority of the presented method. And a simulation result shows that the HEID approach is easily extended in a multiple-input, multiple-output system even with effects of a white noise and parameter uncertainties.