The Stability Analysis And Characteristics Of NCS With Time-Delay

With the wide application of control system, the research of networked control systems (NCS) has been attracted more people's attention. The characteristic of NCS is that the reference input, plant output and control input information in every plant (sensor, controller and actuator) exchange information through network, which makes all users in different places share the resource and co-operation. However, when the distributed applications implement over the control network, it is certainly to make the information collide and retransmit because of the limited bandwidth and weight capability. So there must be time delays during information transmission which not only reduce system performance but also is the main factor causing system instability. The stability and characters of networked control systems with time-delay are analyzed. The main content is as follows:The background, existing problems, the lately development and present research of NCS are generalized. Then the existing reason of time-delay, characteristics of time-delay and its effect on performance of system are analyzed. Aimed at a type of singular controlled plant with a regular and impulse-free characters existing in actual system, the model of NCS is established, and the stability of system and the sufficient conditions of stability for NCS are presented. A numerical simulation example shows that the analysis method is valid and the result is feasible.Then the real-time simulator True-Time based on Matlab/Simulink is introducted. Simulation analysis and the effect comparison of different parameters on system stability are presented aiming at output feedback NCS with proportional-differential controller when control plant is inverted pendulum, while sensor node is clock-driven, and the controller node and actuator node are event-driven. By the simulation graphs of output and control input of the system, the relation between stability and time-delay, data packet dropout rate, network load disturbance, sampling period, transmission rate etc factors is discussed.