A control strategy for a class of cascade systems including saturation elements

We are considering the problem of controlling systems including, in cascade, two dynamic linear subsystems and two static nonlinear elements of the saturation type. Furthermore, the second dynamic subsystem is allowed to be of type one (i.e. include an integrator). The problem is dealt with designing a cascade control strategy consisting of two main control loops. The control signal generated by the outer loop acts as reference input for the inner loop which in turn generates the actual control signal applied to the system. It is formally shown that proposed cascade controller stabilizes the resulting closed-loop system and ensures perfect tracking of step-like output reference signals that are compatible with the system saturating elements.