Random Delay Analysis Of OPNET-based Networked Control Systems

With the rapid development of computer network, communication technology and control system, the network gradually enters into control system forming a new architecture. To use the network channel to share information resources is the advantage of this system, making the system wiring simple and maintain and expand easily. The overall performance of the system has been improved. Networked control systems not only can be used in complex industrial control field, but also has great potential in the field of automotive industry, weapon system, robot industry and aerospace industry. For networked control systems with uncertain network factors, the system performance is not only determined by its own control strategy, but also affected by the network factors. It can be seen that the theoretical research of networked control system and practical application are also very importantThere are many shortcomings and problems in the network control system. The time delay is the core of the research, because the other problems are caused by the delay problem. For example:due to the network node physical space is widely distributed, leading to the fragmented data packaging needs the waiting time is too long, so it uses multi packet transmission; packet loss can be as data packets in the transmission process of waiting for the infinite delay; packet timing disorder is caused by the packet experienced different delay, so delay is the networked control system of personnel concerned focus.In this paper, OPNET network simulation software is used to design the controlled object node and the controller node with the control properties. Firstly, the composition of the delay and the common time delay model are discussed. The effect of time delay on the performance of networked control systems is analyzed. Factors affecting the delay in the network are studied, a wired network and wireless network engineering in the software have been set up. By changing the network packet rate and packet interval, packet size, routing protocol and bandwidth utilization rate, and other important parameters, whether the changes of the parameters affect the time delay and how to affect the delay time are analyzed. The throughput of the network is measured and the change of the throughput is relevant or not to the delay of the changes is analyzed. These researches are helpful to the observation of the change of the real time parameter and the change of the time delay in the network, which play a positive role in improving the real-time performance of the networked control system.