Dynamics Modeling,stability Analysis And Control Of Morphing Aircraft

Compared with the traditional fixed-wing airplane,morphing aircraft could obtain higher flight efficiency and best aerodynamic characteristics via morphying wings according to flight conditions.This dissertation studies the dynamics modeling and stability control of morphing aircraft.The main contents are as follows:(1)Based on Kriging surrogate model and recursive algorithm,the reduced-order model(ROM)for the unsteady response of different thickness airfoils is established.The influence of a variable thickness airfoil on the aerodynamic characteristics is studied by the CFD simulation.According to the developed ROM,the fluctuation of unsteady lift force is analyzed via Monte Carlo method.(2)By using the CFD method and parametric analysis approach,the main influence factors of synthetic jet actuator are analyzed.Furthermore,an optimized cavity shape,which could enhance the aerodynamic performance of active flow control further,is proposed.With the help of the surrogate model technology,the nonlinear ROM for the unsteady response under the excitation of synthetic jet actuator is performed,whose validity and effectiveness are demonstrated via the numerical simulation.(3)For a kind of morphing aircraft undergoing large-scale changes in transition process,the influence of the changing shape on aerodynamic parameter is presented,and the dynamic equation at low angle of attack is derived.Afterwards,based on gain-scheduled control method and slow-varying system theory,the self-scheduled controller is obtained by using the linear matrix inequality(LMI)approach,with the feasibility being validated by using a numerical study.Furthermore,the stability during the morphing process is analyzed via Lyapunov method.(4)By using synthetic jet technology,the flight control of a deploying-and-retreating wing at high angle of attack is studied.The rolling motion equation of morphing aircraft is derived,and a controller with compensation is designed via the sliding mode variable structure control approach.Finally,the feasibility of the proposed controller is verified by simulation cases.(5)For the aeroelastic problem of deploying-and-retreating wing in hypersonic flow,morphing wing is studied as equivalent to an axial moving plate.According to Kane method and modal truncation approach,the dynamic equation of aircraft in morphing process is given.The flutter phenomenon of the morphing wing in transient stage is performed numerically,and a novel morphing strategy is proposed for flutter suppression.At last,the effectiveness of the method is shown via Floquet theory.