The Research Of The Calculation And Application Of Delay Time In IP Network Control System

Networked Control System (NCS) is an integration of networkingcommunication technology and cybernetic theoretic. A NCS connects, the controllers,the sensors and the actuators through one shared networking to form feedback controlloops. Compared with traditional control systems, the NCS has advantages of widecontrol area, high reliability, good flexibility, easy malfunction finding and simpleinstallation and maintenance, etc. But with the communication network inserted inNCS, there are some new problems such as time-delay and lost of packets.In the model of full-duplex-switched Ethernet, the maximal delay time in thecommunication and the design of controller are talked about with emphases. Thewaiting-delay time caused by queuing in the line at the gateway is the main fact of thedelay time. The waiting-delay time would be restricted by QoS in NCS and becalculated with network calculate theory. In this thesis, a class based weighted roundrobin queuing policy is advanced and the maximal waiting-time is calculated.At present, most control systems are computer control systems, so the samplingperiod is related with the network loads and delay time. A simple simulate testingwith star topology structure is processed to testify the relationship of sampling periodand delay time, using NS2.After calculating the maximal delay time in network communicating withnetwork calculate theory and building the discrete model of NCS, a method isresearched to design the digital PID controller with the delay time data received bythe simulate testing before.