Research On Compound ADRC Control Technology Of Quadrotor UAV

In recent years,with the rapid development of science and technology,quadrotor UAV is favored by various fields because of its small size,high control flexibility,strong adaptability to flight environment and outstanding price advantage.However,the flight control system is a typical nonlinear system with many parameters and strong correlation,underactuated and other characteristics.When it is applied in various industries,it will be affected by different interference factors.Based on this,this paper takes the quadrotor UAV as the research object.In order to improve the regulation speed,the ability to suppress unknown disturbance and robustness of the flight control system in the working situation,a sliding mode active disturbance rejection control algorithm is proposed to realize the altitude and attitude stability control of UAV in different working scenarios.The main contents of this paper are as follows:Firstly,the flight principle of "+" structure UAV is analyzed.The mathematical models of the aircraft in translational motion and rotational motion are established by using Newton’s law and Euler’s equation.The dynamic model of quadrotor UAV is constructed by combining the two.The attitude and position parameters in the mathematical model are analyzed briefly,which lays a foundation for the subsequent control scheme design and controller algorithm.Secondly,aiming at the problems of imprecise mathematical model and large amount of internal and external disturbances of quadrotor UAV,active disturbance rejection control(ADRC)algorithm is proposed to control the flight altitude and fuselage attitude(roll angle,pitch angle and yaw angle)of quadrotor UAV.In the simulation experiment under the control strategy,each channel of the quadrotor UAV can reach the expected value and hover stably in 2 seconds,and has a certain ability to suppress the external noise disturbance.Then,aiming at the problem of non-linear function(fal)in ADRC,a new smooth and continuous non-linear function(faln)in the whole region is designed by hybrid interpolation method and improved principle.The nonlinear functions in ADRC are improved by this method,and an improved ADRC is proposed.In order to verify the influence of the improved ADRC algorithm on the performance of the aircraft control system,the flight control performance of the improved ADRC algorithm is compared with that of the ADRC algorithm.The simulation results show that the improved aircraft control system has a speed increase of about 40% and a stronger ability to suppress interference.However,when the parameters change,the flight control system is less robust and cannot meet the requirements of flight operations.Finally,for the UAV controlled object,in order to further improve the robustness and disturbance suppression ability of its flight control system,the nonlinear error feedback rate part of the improved ADRC is designed as nonsingular terminal variable structure control rate,and then a sliding mode active disturbance rejection control algorithm(compound ADRC)is proposed.The experimental results show that,compared with the performance of the first two control strategies,the position and attitude tracking speed of the aircraft control system based on the composite ADRC algorithm is the fastest,and the external disturbance has no effect on the attitude of the aircraft,and the robustness is strong.