Research On Fault-tolerant Control For Quadrotor Unmanned Aerial Vehicle Based On Extended State Observer

Quadrotor unmanned aerial vehicle(UAV)has compact structure,convenient operation,low cost and strong environmental adaptability.It is widely applied in aerial photography,unmanned carrier,reconnaissance and detection,forest protection and other aspects of human life.However,there are still some safety challenges in the actual flight process of the quadrotor UAV,such as actuators,sensors and other communication or connection mechanisms may fail during operation,as well as disturbance from the external environment,which bring great hidden trouble to the safe flight of quadrotor UAV.For the stability of quadrotor UAV,how to deal with the possible faults and ensure the transient performance and steady-state performance of the system is particularly significant.Hence the stability tracking control of quadrotor UAV with actuator fault,sensor fault and external disturbance is investigated in this article.The main work of this article is as below:(1)The motion principle of the quadrotor UAV is introduced and the force analysis is carried out.Meanwhile,taking actuator fault,sensor fault and external disturbance into account,the fault dynamics model of the quadrotor UAV is established.(2)On account of the fault dynamics model,the quadrotor UAV system is decoupled into the position subsystem and the attitude subsystem through the doubleloop control strategy of the inner loop attitude control and the outer loop position control.Moreover,on the basis of the linear active disturbance rejection control(LADRC),the corresponding observer and controller is devised.Wherein the extended state observer could effectively estimate and compensate fault and external disturbance in real time.While the continuous output feedback controller can effectively solve the stability tracking control problem of the quadrotor UAV with fault and external disturbance.Finally,stability analysis and numerical simulation verification are put into effect.The numerical simulation results show that the LADRC has certain anti-disturbance ability and fault-tolerance ability.(3)Focusing on the fault dynamic model of quadrotor UAV system and the fixed-time extended state observer,the fixed-time fault-tolerant control scheme is proposed.On account of the LADRC,the fixed-time extended state observer and the fixed-time continuous output feedback controller are applied to maintain the faulty quadrotor UAV system in the stable tracking state in fixed time.Furthermore,the stability analysis and numerical simulation verify the superiority of this control scheme.(4)Aiming at the fault dynamics model of quadrotor UAV system,the fixed-time prescribed performance fault-tolerant control scheme is proposed.Considering that the traditional performance function can utilize the error conversion method,when the time tends to infinity,the tracking error will converge to the prescribed range.Although the stability of the system could be effectively adjusted,the larger the initial value,the slower the convergence speed.To solve the above problem,the fixed-time prescribed performance control is adopted to achieve the stable tracking control of the faulty quadrotor UAV,so as to ensure that the system can converge within the prescribed time.The transient performance and steady-state performance could satisfy the prescribed performance indicators.Finally,the superiority of this control scheme is verified by numerical simulation.