Active disturbance rejection control for uncertain multivariable systems with time-delay

A new nonlinear control method for multivariable systems with time delay is presented. It is based on a unique active disturbance rejection concept. The proposed active disturbance rejection controller (ADRC) consists of the tracking differentiator, the extended state observer and the nonlinear proportional derivative (PD) controller. In this approach, the systems with time delay in the input are viewed as higher-order systems without time delay in the input, the approximation error between the nominal systems and real systems and other uncertainties, all of which are seen as `disturbance' by ADRC and are actively compensated. The techniques developed here can be effectively used in engineering systems, such as chemical processes, and this is demonstrated by an example.