The Real-time Researching Of Industrial Control System(Network) Based On The Fieldbus

Modern industrial control system (also called NCS, Network Control System) is a distributed and real-time feedback network control system, which differs from the former system (for example, the CCS, the DCS), because all of the real-time measuring data and control data in NCS are delivered through the network, and tasks must be cooperated among all of the network points. Network applied in the control system, which achieve the network and distribution of the field bus equipment control, and also strengthens the communication between the field and upper management. This network control model can co-share the information resource, reduce the wires, extend easy, maintenance conveniently, and have high efficiency, better reliable and flexible. However, there are so many information resource, and the transmission of the data need to use the communication wires time-sharing, but the carrying capacity and the bandwidth of the network are limited, thus, there must be caused the unavoidable data collision, repeat etc., which will reduce the system function, even cause the instability. In conclusion, the real-time scheduling of the information is the key problem in the research of the control network.In the study of the information real-time transmission, traditionally, the real-time scheduling algorithm need to know all of the time-restriction exactly (such as, the carrying time, deadline) and predicted environment also need to be provided. However, in many actual problems, the system's character and tasks usually are fuzzy and uncertainty, the system running environment is also usually unpredicted. When the system running in these unpredicted environments, the exact loading model of the system become unpredicted, some of the traditional scheduling algorithm such as EDF and LLF can not provide the assurance of the system, but cause the system resource wasted largely and even worse.In order to solve these problems, a research is carried out based on the information task fuzzy character. The fuzzy theory are used to analysis the priority of tasks, the period and frequency of the control network are optimized, through the real-time closed loop fuzzy feedback control, the real-time scheduling solve the certainty of the tasks' priority. Ensure the scheduling efficiency of the important tasks and have the better robust with the over loading ability of the system. Contrast to the traditional method, the fuzzy theory can take complicated system's analysis and design easier. At present, the more important is that industrial application is beyond the progress of the theory research. All above the study can promote the cooperation between the theory and the practice, especially the in-depth research of the fuzzy control theory in the industrial network.