Study On Fault Detection Of Networked Control System

With the development of computer network technique, control system theory and application will face the new challenge and opportunity. Network control system emerged as the times require. In this system, some signal, such as detecting , control and matching, will all be transmitted through public data network, yet estimating , control and diagnosis function may be executed distributively in the different network nodes. Compared with DCS, it had many advantages, such as simple control system , less line, higher security, easier information sharing realization , easier extending and maintenance and lower price, so it was applied to the engineering practice. But it had some shortcoming and problems, including no united communication protocol; incompatible with TCP/IP protocol; network inducement delay; losing data package and multicenter transmission. Because of these problems, system stability and control capability were greatly influenced.The main contributions are as follows:Chapter one introduced the background and research content of NCS, summarized study status of it, discussed NCS from the point of network and control, especially in control area. Chapter this introduced meanings and method of network system fault-detecting and diagnosis technique.Chapter two introduced maths modeling, robust observation design, and diagnosing invalidation of actuator through analyzing upper limit of residual error. Simulation results were given. All were based on NCS with delay.Chapter three introduced maths modeling of single package transmission and multi-package transmission under considering noise , controller dynamic feedback and output feedback; a uniform modeling method was brought forward for NCS with data package loss. This chapter introduced delay management with Z transformation, that is to say, residual error was brought with equivalence relation, thus control fault of NCS was diagnosed, and simulation results were given.Chapter four introduced design project for NCS with multicenter and long delay.