The Research Of The Control System Based On The Industrial Ethernet Ring Network

With the rapid development of the information network and the control network, theinformation network is being combined with the control network. The networked controlsystem is the closed-loop feedback control system composed of the controllers, the sensorsand the actuators which are connected via the network. Compared with the traditional controlsystem, it has many advantages such as flexible configuration, remote monitoring, highreliability, simple installation, easy maintenance, low cost and sharable information resources.So the networked control systems have wide applications in intelligent transportation, robotics,industrial automation, aerospace, defense.So far there is a lack of systematic research on the networked control systems based on theindustrial Ethernet ring network. There are many issues to be resolved.Using the network andsharing the channel inevitably brought a lot of problems, such as network delay, packet loss,network congestion and the clock asynchronous. These problems will not only reduceperformance of the control system,but also cause system instability, and makes analysis anddesign of the networked control system based on the industrial Ethernet ring network verycomplicated.To solve the above problem, a communication protocol design for the Industry EthernetRing Network, which is compatible with traditional Ethernet, is presented in this paper. It isdesigned with Verilog HDL. The HDL files are packaged into IP Core. At last,the simulatedresult using Quartus II show that the MAC protocol design for the Industry Ethernet RingNetwork can sends and receives not only the frames of the traditional Ethernet,but also thespecial frames of the Industry Ethernet ring network. It not only meets real-time, high-speedrequirements, but also is compatible with traditional Ethernet.A thorough study is made on the scheduling algorithm and the schedulability analysis ofthe industrial Ethernet ring network in this paper. An IERN-LLF algorithm is presented andproved to be the optimal scheduling algorithm for the industry Ethernet ring network when allframes are released at the same time in this paper. Simulated results indicate that,as comparedwith the EDF and RM algorithms, the frame loss rate of IERN-LLF algorithm is of the lowestframe loss rate in the industrial Ethernet ring network, which means that IERN-LLF algorithmis effective in reducing frame conflict, frame loss, network congestion and improving the stability of the networked control systems.With the applications of the IERN-LLF algorithm to the Industry Ethernet Ring Network,two theorems which give a sufficient condition for scheduling frames and a sufficientcondition for scheduling periodic frames in an Industry Ethernet Ring Network are presentedrespectively.The theorems which give sufficient conditions for stability and asymptotic stability of thediscrete-time time-varying linear stochastic systems are presented and proved in this paper.The packet loss is regarded as a random event and the asymptotic stability of the networkedcontrol system based on the Industry Ethernet Ring Network is researched and simulated inthis paper.With the development of networked control systems, time synchronization between nodesis becoming increasingly important. Although IEEE1588standard has been applied toindustry Ethernet, the oscillator of the clock of the ordinary node may be the quartz crystaloscillator for the cost reasons, time error is always objective reality.The time error of the clock is regarded as a stochastic process in this paper. The theoremswhich give sufficient conditions for stability and asymptotic stability of the networked controlsystems base on time error are presented and proved.