Fault Diagnosis Method And Application For Dynamic Systems

With the development of science and the progress of technology, the systems’ complexity and the investment are becoming more and more big, at the same time, control systems’ safety, reliability, maintainability and so on are also more and more important.The aviation, aerospace, nuclear industry and chemical industry and other ?elds, due to the particularity of work environment, the higher requirements in the aspect of system’s security, reliability and maintainability are proposed. The accidents happen in this kind of systems and cause casualties and huge property losses, which makes people further realize the importance of the fault detection and diagnosis technology, hence, the study on the fault diagnosis and application of dynamic systems has important signi?cance. This thesis,for the actual actuator or sensor faults, by applying an observer-based method combined with the stability theory and the descriptor system approach, the problems of fault diagnosis Method for di?erent dynamic systems are studied. The main content of this thesis can be summarized as follows:1. The scheme is proposed to solve the problem of fault detection for a class of discrete-time systems with sensor faults based on the descriptor system approach. Introduce two kinds of performance indexes to measure the robustness to the disturbances and the sensitivity to the faults. By applying the descriptor system approach, a fault detection observer is designed such that the state error system is asymptotically stable and meets the H∞performance index. Simultaneously, the estimation of the state, output and faults are obtained based on the designed observer. The sensitivity problem of the residual to faults is solved. Simulation results explain the validity of the proposed new method.2. The fault detection method for a class of discrete-time Markovian jump systems including sensor faults is discussed. Set the faults as the systems’ state, de?ne the auxiliary state such that the extended state systems are obtained. A descriptor fault detection observer is designed such that the estimation of state, output and faults are obtained,simultaneously. The observer guarantees the state error system be stochastically stable,the residual to disturbances has good robustness and the residual to faults has the good sensitivity. Numerical simulations show the theoretical results are e?ective.3. The descriptor system approach is used to solve the problem of actuator fault detection for a class of discrete-time systems. When the control inputs, actuator faults and unknown bounded disturbances exist, in term of the descriptor system approach, a fault detection ?lter is designed so that the residual system is admissible and meet the H∞performance index. Based on Lyapunov stability theory, it is proved that the residual system is admissible. The form of the fault detection ?lter is given. Simulation results are used to illustrate the validity of the proposed method.4. The H∞fault detection ?lter design problem for a class of T-S fuzzy discretetime systems is considered, where this systems include actuator faults. For system control inputs, actuator faults and unknown bounded disturbances, the descriptor fault detection?lter is designed to makes the residual system be admissible in the H∞sense. The su?cient conditions of residual system’s admissibility are obtained in form of linear matrix inequality.The forms of the detection ?lter’s parameters are shown. By the designed ?lter, the estimation of states and disturbances are shown. Simulations results are analyzed to verify the validity of the method.5. The fault detection ?lter for vehicle active suspension system is designed by applying a ?nite frequency domain approach. The fault detection ?lter is designed in low, middle and high frequency domain, respectively. The fault detection ?lter problem is converted into H∞?lter problem. According to the generalized Kalman-Yakubovich-Popov(KYP)lemma and the Lyapunov stability theory, the su?cient conditions of the stability of residual system satisfying H∞performance index are obtained in the ?nite frequency domain.The design problems are formulated as the optimization algorithms. The simulation results show the e?ectiveness and practicability of the method proposed.In the end, main results in this thesis are summarized, and the prospects for the future research are presented.