Stability analysis for nonlinear feedback control systems with linear actuators

Often, nonlinear feedback controllers are implemented with linear actuators, which have faster dynamics when compared with non-linear dynamics of the plant and controller models. However, how faster should the dynamics of the linear actuator be to ensure stability of the given nonlinear feedback control system? This note gives an analysis for the underlying stability issues and provides quantitative measures for the linear actuators employed in nonlinear feedback control systems.