Robust ℋ∞ PID control for networked control systems with acceptable noise rejection

In this paper, we study the design problem of PID controllers for networked control systems (NCSs) with polyhedral uncertainties. The load disturbance and measurement noise are both taken into account in the modeling to better reflect the practical scenario. By using a novel technique, the design problem of PID controllers is converted into a design problem of output feedback controllers. Our goal of this paper is in two-fold: 1) To design the robust PID tracking control for practical models; 2) to develop the robust ℋ_∞ PID control such that load and reference disturbances can be attenuated with a prescribed level. Sufficient conditions are derived by employing advanced techniques for achieving delay dependence. The proposed controller can be readily designed based on an iterative suboptimal algorithm. Finally, an example is presented to show the effectiveness of the proposed methods.