Study On Dynamic Characteristics And Security Control Method Of Carrier Aircraft Arrested Deck-Landing

As the key factor to ensure the operational performance of carrier-based aircraft,the main characteristics of carrier landing system are as follows: multi-parameter,high coupling,high-precision and high precision.However,due to the lack of comprehensive consideration the influences of the following three aspects of the dynamics characteristics and safety characteristics,thus causing the simulation accuracy and safety of the carrier landing are hard to be further improved.Firstly,there is a deviation between the behavior of the mathematical model being constructed and the actual physical process because of the neglect of many kinds of nonlinear disturbance factors and many body coupling characteristics.Secondly,the strong oscillatory aerodynamic characteristics and the control theory performance constraints are not fully taken into consideration during the controller design.Thirdly,because of the lack of research on the safe maneuver envelope,it is difficult for the pilot to determine whether the current state is safe based on the landing parameters.For these reasons,this thesis investigates and develops modeling technologies for the nonlinear dynamic system with complete quantity,linear and nonlinear control strategies during carrier landing,parameters marching method,largest positively invariant set solving algorithm and corresponding envelope protection strategy,aiming to provide practical and operational technical support for the flight dynamical and safety characteristics study.The main research issues and achievements in this paper are as follows:(1)Involving in research on the coupling characteristics of multi-body model,which is consisted of carrier-based aircraft,carrier,landing gear and arresting system,a method is proposed for establishing the nonlinear dynamic system of carrier arresting landing with the improved mathematic models,such as arresting hook and arresting gear system.Then the validity of the method is verified through simulation.Subsequently,the comparative study on influences of dynamics characteristic during carrier arresting landing caused by different key parameters is developed.The results indicate the new system can more accurately simulate the coupling characteristics of force and space orientation between the modules,and better reflect the dynamic characteristics of carrier landing under different conditions as well.(2)Transforming the high order nonlinear system into linear differential equations by using frozen coefficient method,and with which the modal characteristics of the natural are solved and a conventional carrier automatic landing control system is designed and analyzed.Taking into account the requirements of the control system robustness and accuracy of the carrier landing,a new linear carrier landing control strategy is presented.Firstly,combining with control augmentation system and automatic control system,the automatic flight control system(AFCS)with strong robustness and lower model accuracy requirement is designed based on quantitative feedback theory(QFT).Furthermore,the new AFCS is crossed linking with a guidance system which is designed with total energy control system(TECS),and the use of particle swarm optimization(PSO)algorithm to complete the controller parameters tuning.The simulation results show the QFT/TECS control system can effectively inhibit the influences caused by various interference factors and improve precision during carrier aircraft landing.(3)A nonlinear optimal landing control system is constructed with the affine form of nonlinear systems as the object of study.Using the Second-order linear optimal control theory for the initial control analytic solution,followed by a combination of the Successive Galerkin Approximation algorithm to solve the HJB partial differential equation,the nonlinear landing optimal control law is calculated.Subsequently,the influences of control accuracy for different order truncations of complete set of polynomial basis functions are analyzed.And then,by introducing the disturbance input,a suboptimal control law of robust nonlinear control strategy with H? is obtained through intercepting the finite iteration results of Galerkin algorithm.The simulation results show that,compared with conventional controller,the new strategy can effectively inhibit the disturbance caused by various disturbance factors on the premise of system stability.(4)Based on the several specific safety criteria during carrier landing,the matching analytic formulas of landing parameters are obtained through the derivation of dynamics equations,and the parameters fitting curves can be solved.Subsequently,to define the curve matching area as the basis,the analysis method of matching characteristic between engaging velocity and landing quality is established with proper safety criteria,and then the landing state space which satisfies with all constraints of safety criteria is calculated.Furthermore,the influences of matching characteristics due to various factors are analyzed as well.The simulation results show that the new analytics can effectively,quickly and intuitively solve the parameter match envelop in different landing conditions.(5)Considering the constraints of landing safety criteria and the dynamic characteristics of aircraft,the research on safe maneuver envelope is carried out.By extending the theory of invariant set and reachable region,the concept of safe set(the largest controlled invariant set within the flight envelope)is introduced.Based on the dynamics characteristics of aircraft and control performance,the safe maneuver envelope which meets all constraints on the affine nonlinear system is solved with level set theory and the landing parameters matching envelope.At last,the safe sets in different carrier landing states are obtained and analyzed.On this basis,the full status boundary protect and control system which guarantees the security of aircraft landing safety is established,in which the control surfaces deflection rates are introduced as input states to simulate the real time delay characteristics of actuators.The simulation results show that the dynamic trajectory of aircraft can maintain in the interior of safe set under the protection of maneuverability control strategy,and the discontinuous characteristic of control outputs is eliminated effectively in the augmented system.