Researches On Fault Detection For A Class Of Sector Nonlinear Networked Control Systems

It is important to improve the reliability and security of the modern control system,becuase it tends to intelligent,complicated and widely used.On the one hand,the phenomenon of random packet loss and parameter uncertainty is common in network control systems.When the node of the system breaks down,the traditional controller will be difficult to achieve the desired performance of control system and even cause paralysis of the whole system.On the other hand,the nonlinear phenomenon is widespread in the actual engineering systems.When the control system is required to have high performance,the nonlinear term of system modeling cannot be ignored.And it does not seem as a simple linearization.Besides,the sectorial domain bounded conditions can describe a large class of nonlinear systems more reasonably.It is very meaningful to study the fault detection technology of networked control systems with sector nonlinearity.In the first chapter,on the basis of studying many domestic and foreign literature,the paper first introduces the background of the subject and significance,the subject status at home and abroad and basic problems of the network control system,as well as the research review of fault detection and diagnosis technology and the fault detection research of the network control system.In the second chapter,the mathematical basis and preliminary knowledge are introduced.The symbolic description and the concept of sector nonlinear constraint are introduced.Besides the Lyapunov stability theory,linear matrix inequality theory and relevant lemma are elaborated.In the third chapter,a scheme of the fault detection and control co-design is studied for a class of sector nonlinear discrete-time systems with random packets loss.Design an Luenberger observer-based fault detector as a residual generators.By using a Lyapunov method,a sufficient condition is derived and proved,which makes the discrere-time nonlinear networked systems exponentially mean-square stable when there is no external,and achieves theH_?performance when there is external disturbance.The solution of the parameters of the fault detection filter and controller of discrete-time nonlinear networked system are transformed into a feasible convex optimization problem of linear matrix inequality,which ensures the residual and error estimation as small as possible.Finally,compared with the proposed method for given controller parameters in literature[60],numerical simulation shows that the method designed in this chapter has better performance.In the fourth chapter,another fault detection strategy is designed for a class of discrete networked control systems with sector nonlinearity and random packet loss,and the object of study for uncertain systems with disturbance and the parameters of the nonlinear term.Design a fault detector based on filter as a residual generators.By using a Lyapunov method,a sufficient condition is derived and proved,which makes the discrere-time nonlinear networked systems mean square asymptotically stable when there is no external disturbance,and achieves theH_?performance when there is external disturbance.Finally,the result of the fault detector based on the form of linear matrix inequality is given.Compared with the filter constructed in literature[42],the simulation experiment shows that the method designed in this chapter has better performance.At last,it summarizes the whole paper,and gives two effective fault detection methods for a class of discrete networked control systems with sector nonlinearity,and points out some problems in the study of discrete networked control systems and the research direction.