H∞ controller synthesis for Networked Control Systems with time delay system approach

In modern control systems, physical plant, controller, sensors and actuators are difficult to be located at the same place, and hence these components need to be connected over network media. When feedback control system is closed via a communication channel, then the control system is classified as a Networked Control System (NCS). The introduction of communication network gives significant advantages, such as reduced installation and maintenance cost and increased system agility. In the other hand, the use of communication network will lead to intermittent losses or delays of the information and may decrease the performance and cause instability. This paper investigates the problem of H_∞ controller synthesis for (NCS). It is well known that H_∞-norm constraint can be used to provide a prespecified disturbance attenuation level, and alternatively to analyze robust stability of dynamical system.The NCS is modelled as a time delay system. The physical plant and controller are in continuous time. Two network features are considered: signal transmission delay and data packet dropout. Our objective is focused on the design of state feedback controller which guarantee asymptotic stability of the closed-loop systems. The proposed methods are given in the terms of Linear Matrix Inequality (LMI). If this LMI conditions feasible, a desired controller can be readily constructed. Finally, we consider an unstable system for numerical example. It is shown that the state feedback controller proposed here make the closed-loop system stable with or without input disturbance.