Network Control System Analysis And Control Research

As the development of communications and network technology, the network based automatic control system are becoming a new application trend. Comparing with the traditional point-to-point control system, the NCS (networked control system) has the advantages of less wiring, lower install cost as well as greater agility in diagnosis and maintenance, and so on. But, because of the intervention of network, the conventional control system meets the new challenges, for example: the network-induced delay, packet losses, the clock asynchronous and so on. The following questions are researched in this paper:Firstly, this paper discusses the factors that affect the performance of the NCS, which will change awfully, when adopting the different approaches of the network schedule, the network types, and the node driven manners. Then it analyses the constitutions of the network-induced delay and the relative factors. Trough the TrueTime simulation toolbox, the simulation model is established, the experiments indicates that the performance of the network will be degraded when time delay and the loss-packet rate are increase.Secondly, according to the different conditions of the network, the models of generalized controlled plant are built, containing these situations: the time delay less than a sample period, bounded time delay under the different driven ways of the controller and the actor, the multi-packet transition under the different driven ways of the controller. Then considering the stability and the performance of the NCS, the guaranteed cost control based on the LMI is put forward. Both of the models of certain and uncertain NCS are built, the theory of asymptotic stability is derived, and by the means of LMI, the feedback control principle is given. The example simulation indicates the effectiveness of the presented method.Finally, for the system which can't establish the precise model, the predict control is raise to compensate the affection of the network. After introducing the state prediction arithmetic which based on the time stamp, the improvement of the traditional predictive control is given. The advanced arithmetic possesses the function of PI controller. Then, taking the advantage of the former arithmetic, the PI generalized predictive control based on time stamp is given. Also, the paper designs the main control project and the network compensator, and analyses the stability of the closed-looped system. The simulation experiment shows that this arithmetic can greatly reduce the affection of the time delay and the packet loss.