Research On Sliding Mode Controller Of Quadrotor UAV Based On Expanded State Observer

Quadrotor UAV has a simple airframe structure,flexible movement,can achieve vertical take-off and landing,simple operation,easy to carry and other characteristics,in the agricultural and military industries have been widely used,and gradually become a hot spot in domestic and foreign research.At the same time,the quadcopter is a representative of a strongly coupled,nonlinear system,whose anti-interference ability is general and its aerodynamic characteristics are susceptible to interference from the external environment.For the complex working environment of plant protection UAVs,flight control methods are particularly important.Therefore,this thesis mainly studies the trajectory tracking and control problem of plant protection UAVs,and its main research content is as follows:(1)The structural characteristics,kinematics and dynamics of the quadrotor are analyzed,and a mathematical model is established based on Newton’s Euler equation.In order to simplify the complexity of the controller design,the controller is divided into two parts: position and attitude.(2)Based on the traditional cascade PID control algorithm,the simulation results show that the control method can complete trajectory tracking without interference,and the control effect is good.However,when there is interference,its tracking effect is average.Therefore,the sliding mode control(SMC)algorithm is used to design the controller.Simulation results show that its robustness,responsiveness and stability are better than the cascade PID.(3)Controller design using traditional Active disturbance rejection control(ADRC)algorithms.Simulation results show that the control method can still achieve more accurate trajectory tracking in the case of disturbance,but its controller is essentially PD control,so its response speed and stability have a certain improvement space.(4)Since the Extended state observer(ESO)is a core part of the ADRC,the SMC controller is designed based on ESO.The jitter in the SMC is first simply processed,and then the traditional ESO is improved to make its estimation of internal and external uncertain total perturbations more accurate.Through the comparison of simulation results of different algorithms,it is proved that the proposed method has excellent inhibition ability,faster response speed and better stability for unknown disturbances,which can improve the flight stability ability of unmanned aerial vehicle system.In summary,on the basis of the traditional algorithm,the controller designed in this thesis not only has the advantages of fast response speed,strong robustness and high stability of SMC,but also can accurately estimate the system disturbance through ESO,with strong anti-interference ability,so that the overall performance of the controller is greatly improved.Finally,the designed controller was used for the plant protection UAV,and the simulation proved that the plant protection UAV could perform tasks in complex environments.