The Study Of Networked Control System Based On Predictive Control Method

Networked control system is a kind of automatic closed-loop control system. In the process of information transfer, some characteristics of network are bound to affect the performance of control system. Firstly, networked control systems have a lot of advantages, such as low cost, flexible configuration, information resource sharing, and increasing the compatibility between any network nodes. Secondly, some problems, such as data delay, loss of data packet, are brought in Networked control systems inevitably. The insertion of the communication network in the networked control systems can induce delay, which may degrade the performance of control systems and even destabilize the system.The study of increasing the performance of Networked control system has evolved over several decades. Some of those methods have limitations and shortcomings. This paper analyzes the problem of data delay in NCS by making exposition and explanation. Some kinds of NCS random delay are analyzed in this paper. Generally speaking, data delay can be classified into two categories:short time delay and long time delay. On the one hand, concerning long time delay, we use grey prediction method to get predictive value and use state observe to compensate random time delay. On the other hand, concerning long time delay, we adopt a predictive control algorithm (GPC), which can compensate the bad effect caused by time delay in network. Specially, by using Neural Network online learning algorithm to recognize the model of nonlinear object, we can make use of GPC to control nonlinear system and to compensate random time delay. The method in this paper can come to a better control result compared to the discrete PID algorithm.It is important for us to prove feasibility of NCS algorithm designed in this paper. Therefore, it is necessary for us to design a simulation of NCS. The platform is made up of some personal computers. One PC is used as controller. Another PC is used as object. There is a PC that is used as network congestion Data Sources. It realizes the network time delay through the transmission of Multicast Communication between controller and object. We use the class of CSocket in VC6.0 to realize data transmission. The data exchange between VC++ and Matlab is achieved by Matlab dll. Finally, the performance of NCS platform verifies the feasibility of control algorithm designed in this paper.