Design of nonlinear digital servo systems using switching of control gains and reference inputs

In this paper, we consider digital control of nonlinear robust servo systems using reference governor. In this method, reference inputs and controllers are switched according to the location of the state of the system, that is, we need to consider nonlinear systems with constraints. Continuous-time controllers are designed using polytopic Lyapunov functions and piecewise linear Lyapunov function. To execute this control scheme, we need to implement controllers digitally. The main issue is to give a criterion of determining the sampling period which guarantees stability of the nonlinear digital servo system