Robust H∞ dynamic output feedback control of networked control systems with congestion control

This paper investigates a robust H_∞ dynamic output feedback controller for networked control systems (NCSs) with a simple congestion control scheme. This scheme enables the NCSs design to enjoy the advantages of both time-triggered and event-triggered systems. The proposed scheme compares the current measurement with the last transmitted measurement. If the difference between them is less than a prescribed percentage of the current measurements then no measurement is transmitted to the controller and the controller always uses the last transmitted measurements to calculate the feedback gains. Moreover, this technique is applied to the controller output as well. The stability criteria for the closed-loop system is formulated using the Lyapunov-krasovskii functional approach. The sufficient conditions for the controller are given in terms of solvability of bilinear matrix inequalities (BMIs). These BMIs are converted into quasi-convex linear matrix inequalities (LMIs) which are solved using the cone complementarity linearization algorithm. A simulation example is used to evaluate how effective the simple congestion control scheme is in reducing network bandwidth.