Research On Aggressive Maneuvering Flight Control For Flying-Wing Unmanned Aerial Vehicle

The maneuverability of UAV is particularly important in the short-range air combat.As the difficulty of the tasks performed is increasing,the demand for maneuverability is becoming more and more urgent.With the superior aerodynamic characteristics,stealth capability and maneuverability,the flying-wing layout UAV has strong strategic value and application prospects in the military field.In this thesis,a type of flying-wing UAV is taken as the research object,and a maneuvering flight controller with good control quality is designed to allow the UAV to perform several aggressive maneuvers.Firstly,the six-degree-of-freedom model of UAV is established,and the performance analysis is carried out.Based on the performance inadequacies,improved methods are proposed.At the same time,the nonlinear characteristics of kinematics coupling and inertial coupling appearing in maneuvering are analyzed.Then,detailed dynamic analysis is carried out for eight typical aggressive maneuvers,and several longitudinal modes and lateral-directional modes are summarized which are used to design the control strategy of each maneuver,that is,discussing how to call the longitudinal modes and lateral-directional modes to complete the specified aggressive maneuver.Next,the controllers required for the maneuver modes are summarized,and the framework of flight control system is given.A decoupling compensation strategy is designed to offset the known nonlinear coupling quantities in the model.Aiming at the problem of insufficient longitudinal damping and directional static instability of the flying-wing UAV,the pitch damper and the lateral-directional stability augmentation control law are designed.In order to avoid the disturbance caused by frequent switching of the controllers,the inner loop takes the angular rate as the controlled variable.Based on the model of nonlinear coupling quantities cancellation,the inner angular rate loop control law is designed with the main and auxiliary structure,which is dominated by robust servomechanism LQR control and supplemented by model reference adaptive control.The robust servomechanism LQR control can guarantee the system robustness,and the model reference adaptive control can suppress the disturbance caused by the parameter uncertainties.The outer loop uses PID controllers and the root locus method for parameter design.Finally,a numerical simulation model is built under Matlab,and the eight typical aggressive maneuvers analyzed above are simulated to verify the correctness and effectiveness of the control strategy and control law.The simulation results show that the flight control system can control the UAV to perform the specified maneuver stably and accurately even if there are internal parameter uncertainties and external disturbances.It has better robustness and meets the requirements of maneuvering flight control.