Composite Anti-disturbance Control Of Quadrotor UAV Based On Disturbance Observer

Due to its excellent performance and low cost,quadrotor UAVs are widely used in military,civilian and commercial fields.However,it is susceptible to many problems such as wind disturbance,actuator failure,model uncertainty and input saturation during flight.Therefore,this paper designs a composite anti-aircraft model for the mathematical model of quadrotor UAV with disturbance,actuator failure and input saturation.The specific research work is as follows:Firstly,aiming at the disturbance and actuator failure problems in the quadrotor UAV,a composite anti-jamming and fault-tolerant control method for the UAV system is proposed by combining the observer with the non-singular terminal sliding mode control method.It can further improve the antijamming and fault tolerance of the UAV system.Two key issues are mainly considered: mismatched disturbance and actuator failure.Mismatched disturbances are estimated by a finite time disturbance observer(FTDO).The nonlinear disturbance observer is used to estimate the total disturbance caused by the actuator fault,so as to ensure that the estimation error converges to zero within a limited time.Finally,a sliding mode surface for estimating disturbances through a non-singular terminal sliding mode control law is proposed,which can obtain the desired trajectory in a limited time and greatly reduce chattering.Secondly,considering the model uncertainty,mismatched disturbance and actuator failure in the quadrotor UAV system,the radial basis neural network combined with the DOBC theory is used to realize the control of the quadrotor UAV.Two nonlinear observers are proposed.The observers are used to estimate the mismatched disturbance and quadrotor UAV system state,matched disturbance and actuator failure existing in the system,respectively,and the estimation error of the observer can be limited within finite time converges to zero.An RBFNN is introduced to approximate the parametric uncertainty existing in QUAV,where the weights are estimated by an adaptive control law,and a finite-time superhelical sliding mode control method is further proposed to effectively attenuate the jitter effect and ensure the finite-time convergence of the tracking error.Finally,the problems of input saturation,mismatched disturbance and wind disturbance(matched disturbance)in the quadrotor UAV are considered comprehensively.Taking the attitude system of the quadrotor UAV as the research object,the problems of input saturation,mismatched disturbance and wind disturbance in the quadrotor UAV are taken as the research object.In this paper,an adaptive finite-time global sliding mode control method is proposed,and a compensation function is designed for the problem of controller input saturation,so as to solve the limitation in the controller design.Tracking error,fast arrival part and global sliding mode surface of virtual control input,adaptive law approximation is adopted for the mismatched disturbance existing in the system and the unknown upper limit of wind disturbance.In addition,the limited limitation of the proposed method is proved by Lyapunov theory.Time convergence performance,and the final simulation results demonstrate the effectiveness of the proposed method.