Performance Limit Analysis Of Control System In Network Environment

With the rapid development of Internet and communication technology,the traditional control system has been unable to meet the needs of people,and the network and we are inextricably linked.Therefore,the combination of network and traditional control system attracts the attention of scholars at home and abroad,and more and more scholars have studied it,so the networked system came into being.The operation of intelligent vehicle,the birth of remote UAV and the operation of artificial intelligence are all related to the network system.Networked system is a kind of control system which can realize the information exchange between components by using computer communication network instead of traditional control system.Compared with the traditional control system,the network system solves the different geographical location constraints among the components,thus realizing long-distance transmission.The network system has the advantages of fast transmission speed,easy operation and maintenance.However,due to the intervention of communication network,there are many new problems in the process of communication in the networked system,such as data loss,coding and decoding,network delay,bandwidth and noise constraints,which affect the system.This paper studies the influence of communication parameters on networked system.In this paper,the stability,performance limit and optimal tracking performance of the control system under the network environment are studied,and the related problems of the networked system are analyzed by using the technology of all pass decomposition,internal and external decomposition and spectral decomposition,as well as the theory of Youla parameterization.The main contents of the study are as follows:In the network time-delay system,by discussing packet loss,noise,bandwidth,coding and decoding,the minimum limit value of signal-to-noise ratio is obtained by frequency-domain method to make the network time-delay system stable.The minimum limit value shows that the signal-to-noise ratio required for the stability of the network delay system is determined by the packet loss rate,coding,unstable poles and nonminimum phase zeros of the communication network channel.For the stability of networked system,the performance limit of networked system with two channel noise and bandwidth constraints is studied.Considering the network delay in forward channel,white noise,bandwidth and white noise constraints in coding decoding and feedback channel,the performance limit expression is obtained by spectral decomposition technology and the method of selecting the optimal single parameter.It is concluded that the performance limit is determined by nonminimum phase zero,unstable pole,two channel white noise,coding and other factors.In the multi input and multi output networked system,we consider that the forward channel and the feedback channel have both channel noise and bandwidth constraints.We use the all pass decomposition and spectral decomposition techniques to obtain the limit expression of tracking performance.The results show that the optimal tracking performance of this kind of networked system is affected by the nonminimum phase zero,unstable pole and direction of the given object.In addition,network communication parameters such as channel noise and bandwidth in communication channel also affect the optimal tracking performance to varying degrees.The above results provide guidance for the future research of networked system.