The Flight Control System Of A Quadrotor Based On Active Disturbance Rejection Control Technique

Multi-rotor unmanned aerial vehicles(UAV)has been widely used in various fields because of its flexible flight capability,small size,light weight,low risk and other characteristics.With excellent flight characteristics,multi-rotor UAVs also have a certain degree of nonlinearity as well as coupling,and will also be influenced and interfered in a complex environment.Therefore,it still needs deep study to improve the stability and resisting ability against disturbance of multi-rotor UAVs.Based on the comprehension of the Active Disturbance Rejection Control(ADRC)technology,this paper will analyze how to apply this technology to the realization of the quadrotor attitude control.First,the construction of the quadrotor aircraft platform,the selection of the basic power mechanism,the design of the avionics system,the measurement of the rotor inertia,the identification of the power mechanism,and the research on fusion algorithm of attitude calculation based on IMU and magnetometer not only ensure that the quadrotor are adequately equipped and the control system is stable and efficient,but also lay the foundation for the follow-up study of the application of ADRC technology for aircraft attitude control.At the same time,the problem of high frequency noise of the sensor is solved emphatically during the process of the research on attitude calculation in order to improve the stability of the system and the realization of the ADRC technique.Second,different from most of the existing papers,the paper presents a model including dynamic characteristics of actuators composed of ESC and motor,as well as the dynamics and kinematic characteristics of the body.Through the detailed analysis of the complete dynamic characteristics of the quadrotor,the key obstacles in the application of ADRC technology in attitude control of the quadrotor are spotted and the countermeasures are therefore found.In practical analysis and application,it is found that the delay effect of the extended state observer is not negligible for the dynamic propulsion system.To deal with that,this paper proposes to increase the PD of control signal for offsetting delay effect,and then apply the ADRC technology,and verify the feasibility of the scheme through numerical simulation,so as to ensure the successful implementation of ADRC.Finally,the active-disturbance-rejection attitude controller is realized on the platform.At the same time,the anti-disturbance experiment is completed.Compared with the PID,the ADRC system has better stability and anti-disturbance performance.In the flight experiment,the attitude control is relatively stable and the response is rapid,and the resistance to external disturbance is strong,which indicates that the implement of the active-disturbance-rejection attitude controller is fairly successful.