LADRC-Smith Controller Design and Parameters Analysis for First-Order Inertial Systems with Large Time-Delay

In the process of modern industrial control, systems with large time-delay are typical problems. Thus in order to get better control effect, it is productive by combining advanced control methods with traditional Smith predictor. The aim of this paper is to present the LADRC(linear active disturbance rejection control)-Smith controller design and parameters analysis for first-order inertial systems with large time-delay, along with the discussion of frequency response and parameters perturbation for systems. To be specific, it is proved that the system is stable when parameters of plant are exactly known. Moreover, a sufficient stable condition is obtained when parameters of plant change. Besides, the step response, stability margin and capability of disturbance rejection are compared when the plant has a different degree of perturbation, and these results make great sense to design the LADRC-Smith controller and regulate parameters for time-delay systems.