Research On Longitudinal Control System Design Of Secure Landing For High Span-chord Ratio UAV

The dissertation mainly investigates the security problem in the landing control systems of High Span-Chord Ratio Unmaned Air Vehicle.Considering that during aircraft landing phase there are strict constraint conditions and drastic changes in velocity and fluences of wind turbulence,the research work designs two control strategies to enhance safety of landing phase from GNC and aerodynamic configuration,which can reduce sensitivity of UAV to wind disturbance and the maintain consistency of flight state.Three typical windfield models and UAV model with wind disturbance are established to draw a conclusion that gust wind is the most harmful on the safety of UAV landing.Analyzing original landing control strategy,we can find that the strategy aggravates sensitivity of UAV and disturbance of angle-loop to gust wind in the flare.From the aspect of GNC,the original guidance law and control law are improved.According to the problem that UAV is sensitive to wind,adopting Sink-Rate guidance methods and TECS(Total Energy Control System)guidance methods to improve landing trajectory and achieve good velocity/altitude decoupling effect.According to the problem that angle-loop is easily disturbance,adopting terminal integration control methods and series control structure to improve controller type and inhibit the violent disturbance of angle-loop.Simulation shows the strategy can ensure landing precision,sharply increase resistance of UVA to the wind,and strengthen the landing consistency and security.From the aspect of aerodynamic configuration,aimed to the UAV with flap,the paper puts forward a landing control strategy based on the flap.Because of the High Span-Chord Ratio UAV has high Lift-drag Ratio,the maneuverability of the throttle is weakened,which leds to reduce resistance of UVA to the wind.Using flap to change aerodynamic configuration can reduce Lift-drag Ratio,restore the throttle maneuverability.Simulation shows the strategy can enhance landing precision,solve the problem of atmospheric disturbance of UAV,and strengthen the landing consistency and security.