Research On Modeling And Longitudinal Robust Control Methods For Hypersonic Morphing Aircrafts

To ensure the high-precision and stable control in the process of deformation and give full play to the combat effectiveness of morphing aircrafts,the dissertation carries out a deep study on the six degree of freedom(DOF)modeling of hypersonic morphing aircrafts and longitudinal robust control methods.The 6 DOF model of the hypersonic morphing aircraft is built as well as its simplified longitudinal motion model.Based on the multi-body dynamics theory,the morphing aircraft is regarded as a system of particles consisted of multiple rigid bodies,and then a 6 DOF model with additional force and moment,from which a simplified longitudinal motion model can be easily derived,is established to afford model for the following research of control method.The longitudinal aerodynamic model of the hypersonic morphing aircraft is established and the aerodynamic characteristics are analyzed.Based on the principle of least squares,three types of aerodynamic model corresponding to span-variation,sweep variation and combined-variation,namely span-sweep-variation,can be identified.The effect of deformation on the static aerodynamic characteristics and the dynamic characteristics during the deformation process are studied with the above-built models.Moreover,the influence of the additional force and moment is studied,further revealing the essence of the deformation.A robust gain-scheduling control method based on the linear parameter variable(LPV)model is studied.Firstly,it establishes the LPV model to get the parametric model with the deformation parameters be adjustable parameters.Then,an poly-tope LPV system and an affine LPV system can be derived from the previous LPV system by appropriate disposition and simplification,which are used to design the longitudinal controller based on output feedback robust gain-scheduling control method and state feedback robust gain-scheduling control method respectively.Finally,numerical simulations are carried out to prove the effectiveness and robustness of the control method.A robust adaptive control method based on dynamic surface is studied.The influence of deformation is considered as part of the aircraft’s uncertainties.Firstly,given the "differential expansion" problem of the back-stepping control,a first-order filter is designed,named as the dynamic surface control.Considering the strong uncertainty and the influence of deformation,adaptive laws are designed to estimate the uncertainties online and correspondingly,some robust items are designed to compensate,thus forming the robust adaptive dynamic surface control method.Besides,the stability of the designed controller is analyzed with the Lyapunov stability theory.Finally,through the numerical simulation analysis,the designed controller is proven effective and robust.This paper utilizes multi-body dynamics method to establish the 6 DOF motion model and the longitudinal model of the hypersonic morphing aircraft,and then accomplishes longitudinal aerodynamic modeling and aerodynamic characteristics analysis.In view of the longitudinal control problem,two kinds of methods,based on robust gain-scheduling control and robust adaptive dynamic surface control respectively,are studied and the designed controllers can complete the control task effectively.The research results of this paper are of great reference value for the control of hypersonic morphing aircrafts.