Study On The Control Method Of Fixed-wing UAV Based On Backstepping Adaptive

With the development of science and technology,the UAV began to gradually into people's vision,its application is gradually changed from military to civilian.As the task of the UAV is increasingly diverse,the ability of the fast execution and the requirement of the accuracy performance of the UAV are also improved,so its flight safety and stability attract more and more attention.The core of UAV control is flight controller.Nowadays over 80% of the mini UAV are using the traditional PID controller,But in some accuracy control cases,the PID controller can't meet the need of rapidity and accuracy at the same time,especially when the rudder surface accidently damaged and so on,the traditional PID control will not complete the control of the UAV,and even have the risk of falling.Based on the actual control of UAV and the shortage of PID controller,in this paper,an adaptive controller for fixed wing UAV Based on inversion is proposed and designed.This controller is based on the adaptive control of the "braking" idea as the starting point,and the controller is derived from the output of the system in real time,which is universally applied to nonlinear strong coupled time-varying systems such as UAV;At the same time it combination the recursive idea of backstepping,which makes the design clear and the controller simple and easy;Firstly,in this paper the mathematical model of the UAV with stationary flight situation is established.Then the transfer function between the actual attitude angle and the input angle of the UAV is deduced,meanwhile,the mathematical modeling of the rudder surface damage is carried out.Based on these,an improved intelligent adaptive PID controller which has better performance than traditional PID is designed,this controller uses the idea of expert control to divide the actual output response into different segments,which designs the different PID controllers and control parameters according to the actual output.So as to improve the overall system of the speed and accuracy;Secondly,the adaptive backstepping controller and the intelligent adaptive PID controller,with the UAV in good condition,are simulated by MATLAB/Simulink.Control performance of these two kinds of controller-in pitch,roll and yaw of the three attitude of UAV-are analyzed.The results show that the intelligent adaptive PID controller is dominant in the fast and the adaptive backstepping controller is dominant in the accuracy;Thirdly,the model of the rudder surface damage is introduced.The performance of these two controller in three attitude of pitch,roll and yaw with the cases of rudder efficiency defect,rudder wedge and rudder solid are simulated and analyzed.The results show that by the time of rudder efficiency defect,the intelligent adaptive PID controller has a bigger overshoot and a longer adjustment time,which could not reach the demand for the rapidity control of UAV's;But the adaptive backstepping controller has a unchanged overshoot and a little longer adjustment time,which can still keep the good control performance.And by the time of rudder wedge and rudder solid,the system output of the intelligent adaptive PID controller cannot track the expected input,So it can't control the UAV,but the adaptive backsteeping controller can maintain the relative good rapidity and accuracy,and complete related tasks of UAV.Finally,the adaptive backstepping controller and the intelligent adaptive PID controller are verified by using the 1680 fixed wing UAV,Through the analysis of flight log,the correctness of simulation analysis is verified.At the same time,it is proved that the adaptive backstepping controller should be applied to the attitude control of the fixed wing UAV.