Robust stabilization in an observer-controller feedback system under nonlinear time-varying perturbations or unmodeled dynamics

In this note a new robust criterion is proposed to analyze multivariable observer-controller compensator feedback systems under additive nonlinear perturbations. In order to stabilize these systems, a more general parameterized observer-controller compensator is introduced, and a design algorithm is proposed for robust stabilization against the nonlinear perturbations. Finally, an example is given to illustrate our results.