I. Introduction
Actuator rate saturation is an important issue for closed loop control systems since it may create significant phase shift and amplitude reduction between the commanded and the actual system states (see Fig.1). Phase shift manifests itself as an effective time delay which, in general, decreases the phase margin of the system resulting in reduced robustness to uncertainties, oscillatory behavior and degraded performance. In flight control systems (FCS), for example, effective time delay introduction due to actuator rate saturation is encountered in almost all Pilot Induced Oscillation (PIO) events and consequently it is considered as an important instigator of PIOs. A PIO can be described as an inadvertent, sustained aircraft oscillation which is the consequence of an abnormal joint enterprise between the aircraft and the pilot [1]. An excellent overview of the effect of rate limiting in PIOs can be found in [2].