Research On Control Technology Of Quadrotor Aircraft Based On Extended State Observer

Quadrotor aircraft has been widely used nowadays due to its small size and high maneuverability.In real flight condition,the performance of quadrotor aircraft will be deteriorated by disturbance like parameter uncertainties,wind drag force and load changes,thus it is meaningful to increase robustness of quadrotor aircraft to disturbance.Sliding mode control is an efficient way to depress disturbance,by introducing sign function,it keeps system states in sliding mode surface.However,chattering phenomenon is one of the great disadvantages of traditional sliding mode control,it decreases the control performance.By treating disturbance as extended states,extended state observer helps to estimate system model uncertainties and external disturbance.Traditional extended state observers are mainly designed based on original system model,its parameters tune procedure will be complex when the original system model is complicated.And it is straight forward to estimate disturbance based on the sliding mode reconstruction system.Since the role of reaching law in sliding mode control is to keep system states on the sliding surface,thus extended state observer designed based on sliding mode surface is proposed in this thesis.The design procedure of extended stated observer is more straight forward and the designed extended stated observer is able to estimate disturbance more completely when mismatched system uncertainties exist.In this thesis,we mainly focus on disturbance rejection control of quadrotor aircraft,extended state observer designed based on sliding surface is proposed to estimate system disturbance,and high order general extended state observer is proposed to increase estimation accuracy.Our works include:(1)Extended state observers designed based on sliding surface are proposed to estimate system uncertainties and external disturbance in the quadrotor attitude control system,sliding mode controller based on extended state observers are designed to ensure attitude errors converge to zero.(2)Extended state observers are constructed to estimate mismatched uncertainties in quadrotor aircraft trace tracking control system.System tracking errors are ensured to be converged by adding the estimated value in the sliding surface.Extended state observers designed based on sliding surface are constructed to estimate total disturbance in the reconstructed system,in this way,chattering phenomenon is depressed and control precision is improved(3)High order general extended state observer is proposed to increase estimation accuracy of extended state observer.The proposed high order general extended state observer is capable to estimate constant disturbance,ramp disturbance and sinusoidal disturbance simultaneously.