Frequency Properties of ADRC

In this paper, the frequency properties of Active Disturbance Rejection Control(ADRC) are quantitatively studies. It’s proved that ADRC can guarantee a nice tracking performance as well as satisfied capabilities of resisting external disturbance and suppressing high-frequency noise. Then the phase margin and the permitted time delay with the variation of parameters of ADRC are quantitatively analyzed. Furthermore, based on the quantitative results, the relationship between the parameter $\hat b$ of ADRC, which is an estimation for unknown gain b, and the time delay permitted in the closed-loop systems is discussed. The simulation results are provided to show the significance of the theoretical results.