Research On Fault-tolerant Control Of Quadrotor UAV Based On Terminal Sliding Mode Theory

With the development of science and technology,quadrotor UAV is widely used for its many advantages,such as simple structure,flexible flight and strong environmental adaptability.In the application,the flight status of the quadrotor will be changed because of disturbances such as flying birds and strong airflow or actuator fault.It will affect the performance of the quadrotor and even cause property loss.In this paper,fault-tolerant control of the quadrotor is realized by designing the terminal sliding mode fault-tolerant controller.The main research contents of this paper are as follows:Firstly,the "ten" quadrotor UAV model is selected.The flight principle is analysed.The conversion relationship is used between the earth coordinate system and the body coordinate system.The dynamics of the quadrotor UAV are established according to Newton's second law and the external moment theorem equation.The problems are aimed that the UAV has disturbances and large chattering during takeoff.Due to accumulating characteristics of input signal using integrator,the integral terminal sliding mode controller is designed.The problems of large chattering caused by the sliding mode control method are overcome.The performances of system anti-shake are improved.The simulation experiments were used to complete the trajectory tracking and fixed-point hovering.Flight mission verifies the effectiveness of the method.It effectively reduces the system chattering phenomenon,and ensures the robustness of the system.Secondly,aiming at the faults of actuator at the pitch angle of attitude and considering the uncertainty of the faults,an adaptive terminal sliding mode fault-tolerant controller is designed.The effects of faults are eliminated because of adaptive compensation.The system's fault-tolerant control performances are improved.Compared with the simulation results of the terminal sliding mode controller without faults,the effectiveness is verified in the adaptive terminal sliding mode faulttolerant control.Finally,it is Considered that there are actuator faults in the quadrotor UAV.It is also accompanied by an unknown disturbance situation.It will further affect the fault-tolerant control performance.A slow time-varying observer is designed to estimate the interference in real time.Conditions are offered to suppress the interference.At the same time,in view of the problem of slow fault-tolerant response speed by using the adaptive terminal sliding mode fault-tolerant control method,the adaptive global terminal sliding mode controller is designed by comprehensively using adaptive theory and terminal sliding mode control theory.And the stability of the system is analyzed.Compared with this method,the proposed adaptive terminal sliding mode method is compared with this method.The effectiveness of the controller's fault-tolerant control is verified.The speeds of system response are improved to deal with faults.