Research On Wireless Network Control System

With the development of computer network technology, control systems based on network begin to be widely used in industry fields, the communications between the control units of industrial control system is turning from point-to-point model to network based model. Such network control systems cut down the connection of sensor and controllers, reduce the complexity of structure of the systems, and improve the reliability of systems. However, kinds of different time-delays are induced into the control systems, and they could make bad effect to the systems. Analysis of the effects from network-induced delay, have become the chief problem of the control system. The existing control networks are usually based on lineate medium, so a series of problems such as cable deployment on surface and wall, and the network maintenance. The fixed cables take much trouble to the applications when some equipment needs to move. Wireless network control systems have some outstanding advantages, such as portable, convenient organizing network, unlimited by geography. So research in wireless network control system does make great sense.First of all, the concept of network control system is introduced, and then the structure of some common control network, medium access and the application occasions are analyzed. Second, the experiment platform of wireless network control system is established, the detailed design idea is given, in hardware, radio frequency module driven by embedded microcontrollers is used, which not only simulates the field control hardware environment, but also make the wireless control system have great agility in protocol software programming. And then, the composition of time delay of wireless network control system is analyzed, the network's measurement guideline is brought forward, the relationsbetween the guidelines and the performance of network are summarized. In order to improve the performance of the wireless network control system with time delay, according to the related technology of wireless local network, we appliance the structure of token bus to the wireless network control system, convert the random time delay to the fixed time delay which has a top ambit. The match between token period and sampling period is analyzed. Finally, based on the hardware platform, we constitute a small wireless closed loop network control system, do some experiment and gain the output response.