Active disturbance rejection control design and analysis for first-order plus time delay systems

This paper deals with the performance and robustness trade-offs of a class of time-delayed systems through traditional active disturbance rejection control (ADRC) and two modified structures applying Smith Predictor and estimate of time delay respectively. The integral absolute error (IAE) of disturbance rejection is investigated with the constraints of robustness in terms of the largest peaks of the sensitivity and complimentary sensitivity functions. Since the uncertainty in the knowledge of the time delay strongly influences the robustness of the controller, thus a robustness requirement in terms of delay margin (DM) is also used to perform the stability analysis and provide guidelines for parameters tuning.