Sliding Mode Control For Networked Control System With Time Delay

The content of this thesis is on studying the control scheme for some kinds of networked control systems with network induced time delay. Networked control systems are feedback control systems wherein the control loops are closed through a real-time network. Networked Control System is a new task of control theory in the 1990s. It has a completely distributed structure where all the control applications (eg. Sensors, controllers and actuators) are connected to the communication network directly. The structure develops data transmitting velocity, makes all users in different places share the resource and co-operation. Networked control systems can be found in industrial automation, building automation, power plant, robot, intelligent vehicle systems, advanced aircraft and spacecraft. This kind of networked control mode has many advantages, such as sharing information resource, simple and fast actuation, small volume of wiring, powerful configuration, powerful system diagnosis and maintenance. However, when the distributed applications implement over the control network, it is necessary to make the information collide and re-transmit because of information transmitted through the limited bandwidth and weight capability. There must be transmitting time delays. So it is important to study the control scheme for the networked control systems with transmitting time delays.In this thesis, a method of sliding mode control based on predictors for the network-induced time delay in network control systems is used to compensate the time delay on the sliding mode surface. According to the networked control systems with different structure, robust sliding mode controllers based on Lyapunov stability theory and rational assumptions are obtained. It not only guarantees systems stability but also systems robustness. Firstly, the conception of networked control systems, introduction and content of networked control systems theory are introduced. Secondly, the network induced time delays of different topology structure are analyzed and then the corresponding plants are modeled. Based on the above, a compensation scheme for the transmitting time delay from controller to actuator is developed. And also a sliding mode controller that makes the system robust is designed. Simulationexample explains the validity of this control scheme. Moreover, a method of sliding mode control based on a predictor for a class special system with state time delay and control time delay is explored, and the maximum transmitting time delay ensuring system global stability is presented. And a sliding surface based state feedback is designed. Simulation example specifies the feasibility and validity of this control scheme. Finally, the development of networked control systems theory and what it is to study for the author in the future is prospected.