Study On Fault Tolerant For A Large Civil Aircraft Based On Incremental Nonlinear Dynamic Inversion

The research of large civil aircraft is a significant signal of a country’s scientific and technological level and comprehensive national strength.It can promote the development of a country’s science and basic industries and can drive a large number of related industries.Large civil aircraft research projects are the major scientific and technological specialties established in the development plan outline.Among them,the flight control system is a safety-critical system during the flight of the aircraft.Failure will have very serious consequences.Therefore,the independent development of a safe and reliable flight control system is important for our civil aviation.It is an inevitable way for science and technology to reach the world’s leading level.With the funding from the Ministry of Industry and Information Technology,this thesis focuses on exploring feasible methods for dealing with the possible faults during the flight process.An incremental dynamic inversion method is applied on the model of aircraft,besides,a fault-tolerant control scheme is also designed.The The three main aspects of the research are described:the nonlinear dynamic modeling of large civil aircraft,the design of nonlinear dynamic inversion control law and the study of incremental dynamic inversion control law,the landing control strategy of large civil aircraft based on the research,and the specific content is as follows:1.Taking civil aircraft as the research object,first,through the general kinematic equation of the rigid body,the dynamic equations of the airflow system variables and the track system variables of the model are derived;secondly,the aerodynamics are established using aerodynamic coefficients and aerodynamic derivatives;then aerodynamic forces and moments are listed,and derive the expressions of thrust,wind,gravity,aerodynamic forces,and moments in the model,and summarize dynamic models including matrix forms used in simulations and non-linear control law designs.The six-degree-of-freedom rigid body nonlinear dynamics was studied,and the longitudinal motion model was simplified.Finally,the open-loop characteristics of the aircraft model were analyzed by Simulink.2.For the control problem of large civil aircraft,based on the concept of fault-tolerant control,the linear controller and nonlinear controller are designed using adaptive control law and nonlinear dynamic inversion method.Then,the linear aircraft model and the nonlinear aircraft model are simulated,and the designed fault-tolerant performance and tracking response performance of the control system are tested and analyzed.In the linear controller design,the adaptive control law that has been applied to engineering design is combined,and the adaptive controller is used to estimate the uncertainty parameter.The estimated value is then used as a compensation of the control system input signal to update the input signal,thereby canceling the unknown uncertainty.Of performance parameters on controller performance.The real-time aerodynamic state of the aircraft is obtained through the acceleration signal,and the required rudder surface deflection increment is calculated.The required increment and the actual deflection value are added to the controlled model.Directly avoid the impact of control system performance on environmental changes,model uncertainties and failures.The simulation results show that when a fault occurs,the angular rate controller can offset the impact of the fault and maintain subsequent stable tracking without fluctuations;the attitude angle controller can also eliminate the fault factors well,but it takes a long time to restore the original state.3.Because the traditional dynamic inversion requires the system model to be accurate,but the robustness is poor,this paper proposes to use the incremental form of the dynamic inversion method to address the nonlinear,model uncertainty and other control problems of large civil aircraft.At the same time,for the landing control of large civil aircraft,the control strategies in different interference situations are discussed.Firstly,the landing problems in the case of stuck rudder surface and wind disturbance are analyzed.Second,the form of incremental dynamic inversion is used to design.A controller with direct fault-tolerance function was simulated.The simulation on the aircraft model verified the effectiveness of the designed fault-tolerant strategy in the case of uncertain model interference and structural failure.The simulation results show that the method not only inherits The characteristics of nonlinear dynamic inverse can also resist interference more quickly and accurately.Based on the above research work,this paper proposes a method of applying the incremental dynamic inversion method to the fault-tolerant control of large civil aircraft,and compares the control effects of some traditional methods.In addition,the design of aircraft fault-tolerant control schemes provides a direction for making up for the difficulty of nonlinear control law design caused by the uncertainty of the control system model,and also provides a new idea for the design of flight control systems for large civil aircraft.