Research Of Control And Scheduling Co-design For Networked Control Systems

With the development of computer technology, control technology and network communication technology, computer control system is required to have higher standard. Networked control system is developed on the basis of this background. Networked control system can solve many shortcomings of computer control system, while we also need to deal with induced delay, packet loss and other problems because of communication network, which makes the analysis and design become more complex. Stability of the control system is the first problem to be solved in analysis and design. Since the data transmit through a special control network, time delay will happen due to the effect of network bandwidth resources and network structure, which would make it difficult to guarantee the stability of control system. The existing researches on restraining the effect of delay are all about specially appointed delay to design the controller, which will either increase the cost of controlling or hardly guarantee the stability of control system.This paper firstly analyzes the characteristics of network delay, and considers the delay as random delay whose change also affect the stability of networked control system. Then propose three delay control methods respectively for different kinds of random delay, which are changing the system structure by designing a buffer to make the delay into a fixed time delay; designing state feedback controller by using pole assignment; taking the time-varying delay as an uncertain parameter by fuzzy control methods to get high system robustness.The scheduling problem of network information is another major research direction in network control system. How to allocate network resources, establish resource allocation and control performance relationships and make the data sending which are through network more reasonable are the problem to be solved. To simplify the analysis and design, the exiting research methods are often based on some assumptions to separate the design of control and scheduling, but in this way the mutual restraint of control strategy and scheduling will be ignored, which is hard to get a good control quality. In this paper, the selecting method of sampling period restrained by control strategy and scheduling is researched. On the basis of reasonable controller, a scheduler including optimized sampling period is designed which can take both controlling and scheduling into account, and the control and scheduling co-design method is proposed which can obtain better control performance. The result of simulation shows that the co-design method is effective and reasonable.