Study On Multi-purpose Simulation Platform Of Networked Control System

Networked Control System (NCS) is a kind of new developing crossing discipline, which integrates control, computer science and network communication. NCS which is researched here differs from the traditional Distributed Control System (DCS) and Fieldbus Control System (FCS) in that the network which it adopts is the public data network instead of the special-purpose Control Network. This brings both opportunities and challenges to NCS. Being incorporated with the public data network, NCS becomes an open, digital-connected system. It also improves its reliability and fault-tolerant ability. On the contrary, the public data network also brings the network-induced time delay which we don't desire. In order to study the influences which the features of the network impose upon the NCS, our job is to establish and develop a multi-purpose simulation platform. Upon this network, we can do many simulations to verify our assumptions and conclusions about NCS.Quality of Service (QoS) greatly affects the performance and stability of NCS. After introducing the research and development situation of NCS, two stability theorems are introduced and the evaluation method of control performance is discussed in the first two chapters.This paper focuses on the general design of the simulation platform hierarchy and each module. As a multi-purpose simulation platform, it should embody the features such as open, scalable and true to reality. With this in mind, this paper completes the general design and partial implementation of the simulation platform. As the central module, the network module plays an important role. It should store and forward the packets, but also have to calculate the time delay and measure the network flux. The most important feature is the combination of network communication and simulation functions. Many investigations about the programming tools were made and finally Java and MATLAB were chosen as the tools. Java is powerful in network and MATLAB is the best tool in simulation. This method combines these two advantages together. Network module is the most important and difficult part. This part introduces the communication model, network protocols and the frequent methods to measure the network. Three methods are used to simulate the real network environment. At last, on the simulation platform, many simulation experiments are conducted to identify the control performance. After the influences imposed by the time delay are analyzed, a few suggestions are given on how to reduce the influence.