The Research Of Fixed-point Landing Control Of The High-aspect-ratio UAV

In recent years,with the development of China's aircraft carrier,the carrier landing of unmanned aerial vehicle(UAV)has become an inevitable trend.As the early algorithm verification of carrier landing control,this dissertation takes a high-aspect-ratio UAV as the control object,aiming at researching an accurate trajectory tracking control method to solve the guidance and control problem of fixed-point landing.The main contents include:Firstly,this dissertation established the dynamics and kinematics equations including wind disturbance parameters.Then the influence of wind disturbance on landing performance is analyzed by combining the aerodynamic characteristics,stability characteristics and glide ability of the UAV.Secondly,owing to the high precision requirement of trajectory tracking for fixed-point landing,a three-dimensional trajectory guidance law based on altitude,forward distance and lateral position is proposed to solve the multi-direction guidance problem of landing.Thirdly,robust servo and model reference adaptive control are applied to design the pitch angle control law of inner loop for model uncertainties and bounded disturbances,and then a longitudinal two-dimensional controller based on height and forward distance is designed in the outer loop to achieve precise tracking of glide-down trajectory.At the same time,the airspeed closed-loop control law is designed in the engine channel to solve the problem of stable flight in a low dynamic pressure.Fourthly,aiming at the weak damping of Dutch roll mode and unstable spiral mode,the lateral stability augmentation control law is designed;and considering the strongly nonlinear coupling in the lateral channel,the roll angle control law of the inner loop is designed by using dynamic inverse and adaptive control;then the control structure of the outer loop is designed,which is dominated by the lateral potion control and supplemented by the course calibration,to realize the accurate landing without lateral deviation and heading error.Finally,the entire flight of fixed-point landing is simulated in Matlab/Simulink.The results show that the control scheme designed in this dissertation has good ability to suppress at least five levels of wind disturbance on the premise of ensuring the landing accuracy and safety,which can meet the requirements of landing error and robustness for fixed-point landing.