IMC-PID Controller Based on Extended State Observer for Second-Order Delayed Unstable Processes with Two Unstable Poles

Abstract

The internal model control (IMC) based PID controller for delayed processes often needs to compromise the set-point tracking response and disturbance response. For the complex second-order delayed unstable process with two unstable poles, there are no simple and effective PID controller tuning rules. In this paper, an IMC-PID control method based on extended state observer (ESO) is proposed. Firstly, in order to reduce the estimation burden of traditional ESO and improve the accuracy of disturbance estimation, a synchronous model ESO (SMESO) is designed. The SMESO considers the information of the nominal model, synchronizes the control input and the system response output in time, thus transforming the delayed process into a perfect model form. Then, through the first-order Taylor expansion and pole-zero cancellation, the parameter tuning rules of IMC-PID controller for the second-order delayed unstable process are derived. Finally, the effectiveness of the proposed method is illustrated by simulation examples.