Capability of the extended state observer for minimum phase plants with unknown orders and uncertain relative degrees

The observing capability of the active disturbance rejection control (ADRC) for the minimum phase plants with unknown orders and uncertain relative degrees is discussed in this paper. The frequency performance of the linear extended state observer (LESO) is analyzed. It is proved that ESO can estimate the required states at the designed speed in spite of a large range of uncertainties. Finally, the results are verified by simulations.