Observer Based Fault Diagnosis And Fault Tolerant Control Of Quadrotor UAV

Quadrotor unmanned aerial vehicles(UAVs)have received a lot of attention in scientific research and practical applications as their ability to hover freely and take off and land vertically,as well as their relatively simple structures and ease of control.However,when it is used,due to its working environment,once the actuator or sensor fault of the quadrotor UAV will cause more serious consequences,the safety and reliability issues of the quadrotor should be given enough attention.Therefore,in this thesis,observers are designed to estimate the actuator and sensor faults of the quadrotor UAV to obtain accurate faults information.At the same time,to ensure the stability of the quadrotor UAV after the fault occurs and ensure that the system output of the quadrotor UAV can still track the given expected value,an active fault-tolerant controller is designed according to the obtained fault information.The specific research contents are as follows:(1)Fault diagnosis and fault-tolerant control of the actuator of the quadrotor UAV is studied.Based on the nonlinear dynamic model of quadrotor UAV,it is transformed into a state space model.In the quadrotor UAV system,the four motors driven by the controller are the actuators.The unknown input observer is designed for the fault diagnosis to obtain the fault information,and the model reference fault-tolerant control method is used to ensure that the quadrotor UAV’s running trajectory can still track the given reference trajectory when the actuator fault occurs.Finally,the MATLAB simulation is used to verify the effectiveness of the fault diagnosis and fault-tolerant control algorithm.(2)Fault diagnosis and fault-tolerant control methods of the quadrotor UAV sensor fault is studied.A nonlinear system model of the quadrotor UAV sensor fault is established,and the effect of external noise is considered,then it’s transformed into the singular system through an augmentation state,then an unknown input observer method is used to estimate the fault information.Finally,a PD feedback compensation fault-tolerant controller is designed to compensate for the influence ofsensor faults.The effectiveness of the proposed fault diagnosis and fault-tolerant controller algorithm is verified by the computer simulations.(3)The actuator fault diagnosis and fault-tolerant control of the uncertainty system of the quadrotor UAV are studied.At present,research on quadrotor UAV systems is carried out under relatively ideal conditions.However,many quadrotor UAVs will have system uncertainties due to various reasons in practice.Considering the uncertainty of the state of the quadrotor UAV system,an adaptive observer is used to diagnose the actuator fault,and a sliding mode tracking fault-tolerant controller is designed to track the given trajectory after actuator fault occurs.Finally,the effectiveness of the fault diagnosis and fault-tolerant control method for the uncertain system of quadrotor UAV is proved by the numerical simulation.