Research On Attitude Control System Of Quadrotor UAV Based On Integral Backstepping Active Disturbance Rejection Control

The quadrotor UAV is widely used in civil and military fields because of its simple structure,small size and easy operation.However,due to the particularity of the application situation of the quadrotor UAV,it is easy to be affected by unknown external disturbance and uncertain internal parameters,which will reduce the flight quality and affect the flight mission.Therefore,it is particularly critical to design a reliable controller for the control system of the quadrotor UAV.Attitude control system is the inner loop control system of UAV.The performance of the controller designed by it is related to the stability of the whole UAV control system.Therefore,the design of good attitude controller is the key step to realize the effective control of UAV.Considering that the quadrotor UAV needs strong anti-interference ability and attitude tracking accuracy when performing tasks,this paper introduces an integral backstepping control strategy to improve the traditional active disturbance rejection controller and applies it to the attitude angle control channel of the quadrotor UAV.The specific research content is as follows:(1)In order to meet the performance requirements of the attitude control system of the quadrotor UAV,the working principle of the flight attitude of UAV is analyzed.By associating the Euler Angle with the inertial coordinate system and the body coordinate system,the dynamics model of the horizontal and rotating motion of the quadrotor was deduced by combining the physics theorem,and the virtual control was defined to solve the problem of the underdrive defect of the model.In order to simulate the influence of wind field disturbance on UAV attitude system,combined with UAV dynamics equation,a floc wind field model was built and the simulation was completed.(2)In order to improve the observation accuracy and the utilization efficiency of the error of the extended state observer,an improved extended state observer is designed.Firstly,in view of the poor smoothness of the nonlinear function near the origin of the traditional ADRC,which is easy to cause system chattering,an improved nonlinear function is designed to improve the smoothness defect.Secondly,the working principle of the traditional extended state observer is analyzed from the error principle.By improving the structure of the extended state observer,the error amount is modified and transformed,and combining with the improved nonlinear function,an improved extended state observer is designed.In order to prove the rationality of the improved extended state observer,the stability and convergence of the improved extended state observer are analyzed.(3)Aiming at the problems of poor interference suppression ability and low tracking accuracy of the attitude system of the quadrotor UAV,the integral backstepping control law is designed by combining the design idea of the backstepping method and introducing integral terms and adaptive factors.Based on the improved extended state observer,an integral backstepping active disturbance rejection controller is designed.Taking the roll Angle as an example,the design process of integral backstepping active disturbance rejection controller is derived.This control strategy combines the characteristics of the two control strategies,preserves the disturbance estimation and compensation function of the active disturbance rejection controller,and improves the tracking accuracy of attitude angle.(4)In order to verify the feasibility of the integral backstepping active disturbance rejection controller,it is applied to the attitude angle control channel of the quadrotor UAV.The simulation verification is carried out from three aspects of response speed,tracking accuracy and antidisturbance performance.Taking the rolling angle as an example,compared with the traditional active disturbance rejection controller,the time to reach the expected value of the integral backstepping active disturbance rejection controller is reduced by 0.4445 s,and the maximum deviation from expected value in gusty interference is 1/28 of that in traditional active disturbance rejection controllers.In addition,integral backstepping active disturbance rejection controller has better tracking performance.(5)Based on the experimental platform,the hover and tracking control performance of the controller designed in this paper is verified.The experimental results show that the integral backstepping active disturbance rejection controller has better tracking accuracy and hovering effect,which is of great significance for the research of attitude control system of quadrotor UAV.