Robust output regulation for nonlinear chemical processes with unmeasurable disturbances

It becomes a problem when the input‐output feedback linearization of nonlinear processes presents unmeasurable disturbances that appear linear in the model and are not in the span of control input space. The prcsented hybrid nonlinear controller, which consists of a nonlinear static state fredback with a series of a adjustable parameters and an internal model, can achieve disturbance attenuation and offset‐free performance. The major advantage of the proposed control system design is to reject disturbance without producing a vigorous control action. A simple estimation method of computing a single parameter that replaces a series of adjustable parameters of the controller is developed. The proposed estimation strategy of computing a single parameter is based on the Lyapunov stability theory. These control schemes are illustrated by an example of a chemical reactor to obtain satisfactory control.