Networked Control Systems Based On Internal Model Control

The networked control systems (NCS) refer to the sensor, the controller and the actuator which constitute the close-loop control system in real time through the communication network. Due to the network, it is inevitable to appear some new problems, such as network delay, packet loss and so on, which will reduce the performance of the control system, or even let the system unstable. Some researches are done about the NCS based on the internal model controller in Truetime1.5.Firstly, make a simulation on the NCS based on the one-degree-of-freedom of the internal model control. The simulation results show that the network delays do not need to be measured, identified or estimated on line, and the nodes do not need the clock signal synchronization, but the system has better dynamic performance and strong robustness and anti-interference ability.Secondly, make a simulation on the NCS based on the two-degree-of-freedom of the internal model control, to discuss the adjustment problems of the quickness and the anti-interference ability, in order to improve the dynamic performance and anti-interference ability of the system.Lastly, make a comparative simulation study between the NCS based on the new Smith predictor and the NCS based on the internal model controller from the structure.The simulation results show the choice of strategy of the new Smith predictor is more flexible than the internal model controller, but the adjusting parameters of the internal model control is relatively less than the new Smith predictor. Both of them are also suitable for the NCS with random, time-variant or uncertain network delays which are larger than one, even tens of sampling periods, or with the changing plant model (parameters). Because these two control algorithms are based on the method of the "soft" changing control system structure, which is easy to realize, it will provide some theoretical foundation and flexible options scheme for the wide application and implementation of the advanced control strategy in the remote complex network environments. So it has a wide prospect for the application in projects.