Analysis of Active Disturbance Rejection Control for Processes with Time Delay

Time delay is very common in industrial process control. The original active disturbance rejection control (ADRC) method is not quite suitable for processes with large time delay, thus several methods were proposed to overcome this problem recently. This paper will analyze a modified ADRC for processes with time delay. We transfer the proposed configuration into an internal model control (IMC) configuration, and shows its advantages and disadvantages. Tuning of the modified ADRC is then discussed in the IMC framework. Simulation examples show that the modified ADRC can improve the performance of the original one with a larger observer bandwidth, while there is still limitation on the controller bandwidth.