Design And Implementation Of Quad-rotor Control System Based On Active Disturbance Rejection

Due to the advantages of simple structure,strong maneuverability and low production cost,quad-rotor aircraft has been widely used in military and civil fields in recent years.The selection of the control algorithm and the design of the control system are the key to the successful completion of the four-rotor aircraft mission.Based on active disturbance rejection control(ADRC),this paper completed the research on cascade ADRC hover control,attitude control and height control,and independently built a four-rotor aircraft platform to verify the feasibility of the algorithm studied.This paper mainly includes the following aspects:1.Establishment of nonlinear mathematical model of four-rotor aircraft.The rigid-body dynamics analysis method was used to model the quad-rotor aircraft,and a simulation platform for the control system of the quad-rotor aircraft was built in the MATLAB/Simulink environment.In view of the nonlinear,underdriven,strongly coupled and uncertain characteristics of the quad-rotor aircraft system,a quad-rotor aircraft control system is designed by using active disturbance rejection control technology,and a cascade ADRC controller is designed for hover control simulation.Linear active disturbance rejection is used for the outer loop of position,and classical active disturbance rejection is used for the inner loop of attitude.2.The platform construction of four-rotor aircraft,from the most basic power mechanism selection to the design of flight control board,to the attitude solution and inertial navigation algorithm research based on the fusion of IMU and magnetometer,lays the foundation for the subsequent application of the new controller.A second-order butterworth digital low-pass filter is designed to deal with the high-frequency noise.In the aspect of attitude calculation,extended Kalman filtering algorithm is designed to obtain the real-time attitude state of aircraft.In the aspect of inertial navigation fusion,an improved Kalman filtering algorithm with time delay correction is proposed to estimate the position and speed of the aircraft due to the hysteresis of the position sensor(barometer /GPS).3.The cascade ADRC controller is also designed to control the attitude loop and height loop of the four-rotor aircraft,which is nonlinear,underdriven,strongly coupled and vulnerable to external interference.The attitude outer loop(Angle)is controlled by linear ADRC,while the attitude inner loop(angular velocity)is controlled by nonlinear ADRC.The height loop adopts position PID+ velocity PID+ acceleration(ADRC).The attitude control and height control of active disturbance rejection are realized on the physical platform.In the four-rotor flight experiment,the aircraft attitude control is stable,the response is rapid,has a strong ability to resist external disturbances,height control can also achieve good results.