Damage-mitigating Control For The Wing Of Hypersonic Flight Vehicle

As a new generation of strategic aircraft,hypersonic flight vehicle suffers some complicated aerodynamic characterics such as thin shock layer、viscous interference、entropy layer、high temperature effect and low-density effect which will creat more complicated aerodynamic load distribution on its surface.these complicated aerodynamic disturbances makes the structure of the vehicle accumulate fatigue damage easier as time goes by,when the accumulated damage reaches a critical point,the structure would be totally destroyed,and may lead to some flight disaster.as the principle force bearing component,the wing has to bear the weight of the vehicle as well as the impact imposed by aerodynamic disturbance and heat which is caused by collision between the hyperflow particle and the surface of the wing.Therefore,some key components of the wing are the primary cause of fatigue damage.To ensure the structural reliability of the wing in entire flight envelope and extending the cycle usage of the hypersonic flight vehicle,this thesis studies the structural mechanics model and damage model of the section of wing.And then,by analyzing the key variables of the aircraft which have the greatest effect to the structural damage accumulation,three corresponding damage-mitigating control scheme are proposed for hypersonic flight vehicle wing.the main works of this thesis are given as follows:Firstly,by stress analyzing the root of the wing spar,we can acquire the realtime stress condition of the spar during the flight of the hypersonic flight vehicle.The damage model is constructed which reflecting the damage evolution of the wing.Based on the kinetic model of HFV and the damage model,the effects of flight height,velocity,angle of attack and aileron deflection angle to the damage characteristic are analyzed to determine the crucial variable which affects the damage the most.Secondly,stress analysis of the wing section is conducted to determine the most vulnerable section,and use the damage information feedback of this section to design the controller.And then clarify the theory basis of prescribed performance,combining damage model and dynamical model,the attitude and longitudinal prescribed performance damage-mitigating controller is then designed respectively to mitigate the damage under certain flight performance.Thirdly,we introduce the theory basis of optimal predictive control of nonlinear system and the damage-mitigating scheme based on the optimization of objective function concerning weighting of performance and damage-related variable.And then design the attitude and longitudinal predictive damage-mitigating controller,which can adjust the weight online in the predefined range based on the damage rate,and the designed controller can mitigate the damage substantially while guaranteeing that the performance stays in some range.Finally,in consideration of the fact that the dynamic property and regulation time of tracking error can’t be known in advance by using the optimal predictive damage-mitigating control,using the thought of prescribed performance,we bring in the predesigned performance function to the objective function to change the optimized target such that the range of the tracking error stays within the region enclosed by the performance function,and then design the optimal predictive damage-mitigating controller which weighting the damage-related variable and performance.And then the damage-mitigating control under controllability of performance can be achieved.