Research On Risk Analysis And Control Strategy During Carrier-based Aircraft Landing

In all the working stages of the carrier-based aircraft,danger coefficient of guidance and landing phase is the most highest.It is most likely to appear serious accidents in this phase.Therefore safety of the aircraft is one of the most important technical problems of the carrier.There are full of risk in the approach and landing process for an aircraft.State deviations in approach phase easily result in accident of hitting the ramp so that the aircraft has to wave off.Off-center and off-yaw of touchdown point in the terminal landing maybe cause fracture of arresting gear or rollover for the aircraft due to unbalanced stress.Consequently,there are significant theoretical research and practical application to effectively analyze the risk of guidance and landing and take the corresponding control strategies in the landing process.Research objective of this paper is aircraft safety.Regarding artificial landing and automatic landing,this paper respectively carries out risk analysis and adopts pointed control strategies to reject risk.First of all,this paper is from practically behavioral characteristics,action feature and behavioral strategies of pilots,and establishes a pilot model with high personification feature,which outputs discrete action series.Hierarchical design is adopted so that pilot model is resolved into information acquirement module,landing risk model,focus modes switch,desired action calculator,random error probability module and delay link.Capability indices are introduced,including information acquirement capability,response capability,distraction capability and action accuracy.Different combination of capability indices can simulate difference of different level pilots.This pilot model contains communication interface with LSO,which can respond to LSO commands and cooperatively simulate with LSO auxiliary decision system.In the next place,risk model of aircraft guidance and landing process is established.According to different phases of guidance and landing,risk is divided into approach flight risk and landing risk.Modeling method of approach flight risk model is raised depending on baseline method.On basis of plenty of sample data of experiment on the flight simulator,regional division and envelope distribution of approach flight risk is determined and model parameters of approach flight risk is quantified.In the meantime,principle of predicting trajectory and touchdown point is proposed by analyzing trajectory characteristic.Plenty of simulation samples are acquired by pilot model on the flight simulator,and linear node envelope of typical trajectory of the aircraft is drawn.Nonlinear function of real-time landing states and future touchdown point is built.On basis of node envelopes,core parameters of landing risk mathematic model can be acquired.Different focused information in artificial and automatic landing is fully considered so that guidance and landing process risk is broke into automatic landing risk and artificial landing risk,which lays the foundation of control strategy of these two landing modes.Then,aiming at artificial landing,control plan of LSO assistant decision rejecting artificial landing risk is designed.Principle and step of forming LSO commands is formulated.Rational analysis of commands is finished to decide possible boundary and pilot action.Method of quantified trigger boundary of commands is designed and typical commands is simulated and verified.Optical trigger boundary is decided according to artificial landing risk so that LSO command set is formed.Cooperatively simulating system of LSO assistant decision model and pilot model is established,which is simulated and verified by four typical conditions.The simulation comparison demonstrates effectiveness of LSO assistant decision rejecting artificial landing risk.Finally,aiming at automatic landing,multiple guidance law and switching strategy rejecting automatic landing risk is designed.According to automatic landing risk and disturbance of airwake,time varying weight MPC guidance law,MPC with risk term guidance law and rejecting airwake disturbance guidance law is put forward on the base of model predictive control(MPC).Weights of state term and control term in time varying weight MPC performance are calculated from approach flight risk model.The addition risk term in MPC with risk term is acquired from landing risk model in real time.What’s more,combining with corresponding theory of positively invariant set and quadratic boundedness,guidance law rejecting airwake disturbance is proposed,which not only rejects airwake,but also eliminates landing state deviations.All the guidance laws are calculated by linear matrix inequalities(LMIs).Furthermore,this paper put forward switching strategy of above three automatic landing guidance laws.Different guidance law is utilized in different phases to pointedly reject corresponding automatic landing risk and disturbance.