Stability and L ₂-gain analysis of Networked Control Systems under Round-Robin scheduling: A time-delay approach

This paper analyzes the exponential stability and the induced L ₂-gain of Networked Control Systems (NCS) that are subject to time-varying transmission intervals, time-varying transmission delays and communication constraints. The system sensor nodes are supposed to be distributed over a network. The scheduling of sensor information towards the controller is ruled by the classical Round-Robin protocol. We develop a time-delay approach for this problem by presenting the closed-loop system as a switched system with multiple and ordered time-varying delays. Linear Matrix Inequalities (LMIs) are derived via appropriate Lyapunov-Krasovskii-based methods. Polytopic uncertainties in the system model can be easily included in the analysis. The efficiency of the method is illustrated on the batch reactor and on the cart-pendulum benchmark problems. Our results essentially improve the hybrid system-based ones and, for the first time, allow treating the case of non-small network-induced delay, which can be greater than the sampling interval.