Fault Diagnosis And Fault-tolerant Control For Aircraft Attitude Control System

With the rapid development of aerospace technology,the structure and mission requirements of aircraft are becoming more and more complex.Once a part of an aircraft fault,it may lead to an aviation accident.In order to improve the safety and reliability of aircraft and reduce accidents,the following work has been done in this paper:For the fault diagnosis of flight control system with external disturbances,this paper presents a fault diagnosis algorithm based on interval observer.Firstly,the fault model of actuator and sensor is established.Then,an interval observer is designed for the flight control system.The upper and lower bounds of the interval observer are used as fault diagnosis thresholds interval.It overcomes misinformation and failing to report caused by inaccurate threshold selection in traditional observer fault diagnosis methods.Finally,taking the longitudinal motion of flight control system as an example,the results show that the fault diagnosis method in this paper can detect the fault quickly and timely when the system fails,and meet the requirements of fault diagnosis.For multi-input LQ problems in which partial actuator faults result in control failure,this paper establishes the concept of resemble redundancy and designs resemble redundancy fault-tolerant feedback controller First,all actuators is divided into two parts:reliability subset and unreliability subset.And then,utilizing the multi-loop couple,regards reliability subset as redundancy of unreliability subset.A fault-tolerant feedback control algorithm is presented based on LQ optimal control.Finally,taking the longitudinal motion equation of flight control system as an example,the results show that the system can still operate stably and has a certain optimality under the action of the controller designed in this paper when some actuators fail.For failure risk analysis of aircraft parts with few sample data,this paper presents a fault risk analysis algorithm based on Monte Carlo method.Firstly,this paper introduces the basic process of risk analysis and gives the calculation formula of fault risk value.Then,the failure probability model of components is established.The failure of components is simulated by Monte Carlo to solve the problem of fewer sample data.Finally,based on the above theoretical knowledge,the fault risk analysis of a certain type of engine is carried out,and the corresponding improvement measures are put forward according to the fault risk value.