Stability Analysis Of Linear Networked Control Systems With Uncertain Time Delay

Networked control system (NCS) is the collection communication network and control system in one of the more complicated control system. It has many advantages, such as resource sharing, easier expansion and maintenance, less connection, high efficiency, reliability and flexibility, etc. However, because of introducing the network into traditional control system and the limits of the network bend, so that it is inevitable that there exits the networked-induced delay, time sequence confusion and data packet dropout, message collision etc. They degrade the performance of control systems. Therefore, a research is needed in networked control systems.In this thesis, the system is to be controlled as a class of networked control system with time-varying delay and parameter uncertainties, some factors are ingeniously taken into account appropriately, such as the network-induced, out-of-order packets and packets loss, as well as external interference, making the model of more system close to reality. Based on the built control model, we discuss several common control problems, in which we use Lyapunov stability theory, linear matrix inequalities approach, integral inequality to get the sufficient condition of system meeting the asymptotical stability and guaranteed a certain performance index, and based on this, we attain the corresponding designing method for control law with less conservation. This article discusses the following major elements:1.The stability and designing method for control law of the uncertain networked control system with time delay:Based on the establishment of the system’s model, making use of Lyapunov stability theory integral inequality free weighting matrices method and linear matrix inequality (LMI) approach to prove a sufficient condition for the stability, while state feedback controller deign method was given. The conclusions are presented in the form of LMI. Using the LMI toolbox in Matlab a numerical example is given to show the effectiveness and reasonability of conclusion.2.The robust H∞control of the uncertain networked control system with time delay: For the presence of external disturbances on the basis of the existing model, fist we add the external disturbances to the existed mode and then we get the new system model, second by the Lyapunov stability theory and the linear matrix inequality(LMI)approach proving the sufficient condition that the new system satisfies the robust stability, and then we obtain the way to design the robust H∞controller. Finally, using the Matlab LMI Toolbox a numerical example is provided to illustrate the effectiveness of the conclusion.