ABSTRACT
When a linear control system is operated in conditions which cause actuator saturation, it can exhibit nonlinear behavior such as local stability, finite disturbance rejection, and performance degradation. In this chapter we provide some tools, based on the Popov Criterion, which allow the designer of a control system to explore the following simple idea: does robustifying a linear controller to sector bounded nonlinearities at the input improve its performance when operating in saturation? The idea is based on the well known observation that when the input to the saturation element is known to be bounded by some r > 0, then the saturator can be modeled locally
sat(g)
Figure 1: Saturation locally sector bounded as parameterized by r.
