The Characteristics Analysis And Research About Transmission Time Delay Of Industrial Ethernet

With the enlarge of control system scope, network control systems are used more and more, as a successful information network technique industrial Ethernet is showing its advantage in control networks. There exist many agreement standards of fieldbus in industry, under the circumstantial of multi-agreement existing together, Ethernet is extending to the control level and it is a hope of unifying the fieldbus. In network control system, control, sense organ and execute organ as absolute nodes connect with network. Thus, the system cable is reducing and the system is easy to maintenance, but the disadvantage is appear with the network, for every node transmits information time-sharing by network and time delay exist inevitably. The current control systems of Ethernet consider network transmit time-delayτonly, but there is no theory base in country inside and outside references for network append time-delay, so current industry Ethernet exist some instability.This paper gives a system summarizer for Ethernet development history and study status quo, starting with Ethernet medium accessing CSMA/CD method educes network time-delay. Nodes visiting rate is random, so network time-delay is a random variable, if regarding the information which send by nodes as customer, regarding fieldbus as information desk, thus a queue system is coming, setting up a model and analyzing network transmit time-delay using queuing theory, then we can obtain that sending time-delay and queuing time-delay caused by conflicts among network tache in network control systems, and we can know the main factors which affect channel utilization rate. Analyzing time delay impact to the system capability, educing some account formulas and go along data emulator. Base on the analyzing of network time-delay, the network control system is modeling for a uncertainty disperse time-delay model, using Stability theory of Lyapunov, discussed the system stability. Combining with a given quadratic performance index, a necessary and sufficient condition for the existence of guaranteed cost controls is derived, control parameter and guaranteed cost value of guaranteed cost control is be given using linear matrix inequalities(LMI )through demonstration. Lastly, the paper illustrated the validity of this method.