A root locus approach to designing tracking controllers in systems with saturating actuators

This paper presents two modifications of the classical method of root locus, which facilitate the design of controllers for tracking random references in the presence of actuator saturation. We begin by studying admissible closed loop pole locations for tracking random references. Then we study the impact of actuator saturation using the method of stochastic linearization, whereby the saturation is replaced by a quasilinear element, leading to the notion of saturated closed loop poles. As a result we obtain the so-called saturated root locus, and use it for controller design.