Adaptive Observer Based On Fault Diagnosis Of Flight Control System

Along with more and larger scale of the control system, the failure probalility of system appear to be also more and higher, how to improve the safety and the reliability of the control system, has increasingly become a hot topic to be solved in the control field. Most of the exiting results about nonlinear fault diagnosis observer always focus on ensuring the accuracy of fault estimation and the sensitivity of fault detection. Given the increasing needs of modern industry systems for safety and reliability, the requirements for the real-time characteristic, quickness, robustness and isolability of fault diagnosis cannot be neglected any more. The increasing requirements bring a lot of new difficult research issues to be solved for fault diagnosis observer design method, which are classified as unknown disturbance decoupling-based diagnosis method and parameter estimation-based diagnosis method, the research for improving high performances, e.g., the real-time characteristic, quickness, robustness, isolability of nonlinear fault diagnosis methods meets the needs of the developing safer complex industrial control procedures.The flight control system is an important part of aircraft, flight control system is the main used to stabilize the aircraft attitude, track keeping, in various states of enhancing stability of an aircraft, improving quality and enhancing the maneuverability of aircraft mobility.The nonlinear systems under consideration contain Lipschitz-like nonlinearities, modeling uncertainties, and may be harmed by time-varying faults. Based on some appropriate assumptions on the monitored faults and a persistent excitation condition, a residual for fault diagnosis is designed in a constructive way by developing a novel nonlinear adaptive observer. Moreover, three design functions are given for the choice of the gain of the observer, which can maintain prescribed levels of the speed of convergence of error systems, the insensitivity to the complement faults and the sensitivity to the monitored faults, respectively. The number of faults which can be completely diagnosed is independent of the number of output sensors. Given a set of possible faults, the sensitivity of the residuals to the monitored faults and the insensitivity to the other complement faults are rigorously analyzed. A simulation example is given to illustrate the effectiveness of the proposed fault diagnosis method.