ADRC with Feedfoward Control For Time-Delay Systems

A novel Active disturbance rejection control (ADRC) with feedforward control is proposed for time-delay systems. The feedforward control, which is inspired by the classic Smith predictor, is added to the original ADRC scheme and tuned to improve the reference tracking performance. The ADRC is mainly tuned to reject total disturbance including model uncertainties and external disturbance. The feedforward control does not change the poles of the main closed-loop system and the stability of the main closed-loop system depends on the conventional ADRC whose stability has been solved theoretically. A first-order plus time-delay (FOPTD) system is used in simulation study where the increasing system order method for time-delay system is used in ADRC. Simulations for reference tracking, external disturbance and variations of time-delay, time-constant and process gain of the plant show that the proposed ADRC with feedforward control provides more effective tracking performance and disturbance rejection abilities than the conventional ADRC for time-delay systems.