Research On Quadrotor Flight Control Based On Fractional-order Active Disturbance Rejection

In recent years,quadrotor unmanned aerial vehicle(UAV)has received more attention as an alternative to more expensive and complex manned systems.It has the advantages of small size,ease of use,low cost,etc.,in the technologically advanced modern life plays an important role in.However,the quadrotor UAV is a system in which each channel affects each other,is multi-variable,and is sensitive to disturbances,and is susceptible to external interference during flight movement.In order to enable the UAV to complete the given trajectory tracking accurately,quickly and efficiently,The research on the control algorithm of quadrotor UAV becomes very important.In this paper,based on the fractional-order active disturbance rejection control technology,the relevant research on the flight control of the quadrotor UAV is carried out.The main research work includes the following aspects:1)The working principle of the quadrotor UAV is analyzed,and the motion forms of the quadrotor UAV are divided into translational motion and rotational motion according to the basic knowledge of dynamics,and the dynamic model is established by Newton’s second law and the resultant moment theorem.2)The basic principle and structure of the traditional ADRC controller are analyzed and expounded.In view of the unsmooth problem of the nonlinear function fal in the traditional ADRC,the inverse hyperbolic sine function is used to replace the commonly used extended state observer in the traditional ADRC.The nonlinear function fal,an improved active disturbance rejection controller is designed.The improved ADRC is used to control the attitude system,and simulation experiments are carried out.The curves are more rounded.In order to explore the observation accuracy of the improved expanded state observer,the observation error experiment of the expanded state observer was carried out,and the results showed that the observation error of the improved expanded state observer was much smaller than that of the traditional expanded state observer,and the accuracy was higher.3)In order to further improve the control accuracy,a fractional-order PD control law with better robustness is used to replace the nonlinear state error feedback control law in the improved ADRC in this paper,and a fractional-order ADRC is formed.The height and three body attitudes(roll,pitch,yaw)of the quadrotor UAV are controlled and simulated by the fractional-order active disturbance rejection controller.The results show that,compared with the performance of the flight control system of the quadrotor UAV under the traditional ADRC and the improved ADRC control strategy proposed above,the position and attitude tracking of the aircraft control system based on the fractional ADRC is the fastest,The error is the smallest;in the case of external interference,the adjustment time is the shortest,the overshoot is the smallest,and the performance is the best.4)Combined with nonlinear PID controller and fractional-order active disturbance rejection controller,a dual closed-loop quadrotor UAV trajectory tracking controller is designed.A nonlinear PID is designed for the position control system with high static error requirements,in which a tracking differentiator is designed to solve the difficult differentiation problem caused by the drastic change of the desired state to ensure that the desired signal is smooth and differentiable,and the parameter adjustment is used.In order to reduce the error of position control.For the attitude control system with high antiinterference ability and high speed requirements,a fractional-order active disturbance rejection controller is designed,so that the quadrotor UAV can keep up with the desired attitude accurately and quickly,and the trajectory tracking experiment of the quadrotor UAV is completed.