Research On Prescribed Performance Fault-Tolerant Control Method Of Quadrotor UAV Under Actuator Fault

The quadrotor UAV has the advantages of simple structure,easy to carry,simple operation,and flexibility,etc.At the same time,the military,agriculture and other fields also have a wide range of demand for the application of quadrotor UAV,so the quadrotor UAV control problem has become a key research topic for researchers.With the development of UAV control technology and the complexity of flight conditions,the control requirements of quadrotor UAV systems have been continuously improved.Due to the advantages of fast convergence and improved transient and steady-state performance,the prescribed performance control of quadrotor UAV has become a hot issue for research.At the same time,in order to meet the actual situation,considering the problem of actuator faults during the flight of the quadrotor UAV,based on the existing research results,this paper studies the fault-tolerant control problem of the quadrotor UAV system under the prescribed performance strategy based on sliding mode control and backstepping control strategy.The main research work is summarized as follows :Firstly,at the beginning of the quadrotor UAV control system research,the "X" type quadrotor UAV model is selected and the flight principle under ideal conditions is analyzed,then the mathematical model of the quadrotor UAV system is constructed based on the interconversion relationship between the coordinate systems(ground and airframe coordinate systems)and the Newton-Euler method.The foundation is laid for the subsequent design of the system control strategy.Secondly,an adaptive prescribed performance sliding mode fault-tolerant control strategy is proposed for the quadrotor UAV with unknown aerodynamic damping coefficients and external disturbances,actuator faults and transient and steady-state performance constraints.The position subsystem uses an adaptive control method to estimate the actuator faults and damping coefficient,and proposes a new prescribed performance sliding mode fault-tolerant controller under the transient and steady-state performance constraint;for the actuator faults and unknown external disturbances of the attitude subsystem,a prescribed performance sliding mode fault-tolerant control method based on disturbance observer is proposed.Using Lyapunov stability theory,it is demonstrated that the control system is consistently and eventually boundedly stable and the tracking error satisfies the prescribed transient and steady-state performance constraint.Meanwhile,Matlab simulation results verify the effectiveness of the proposed control method.Then,a prescribed performance global fast terminal sliding mode fault-tolerant control scheme based on finite time extended state observer(FTESO)is proposed for a quadrotor UAV in the presence of concurrent external disturbances and actuator additive faults.An FTESO is designed for the position and attitude subsystems,respectively,to observe in real time the lumped disturbances consisting of external disturbances and actuator additive faults.Then the prescribed performance strategy and the terminal sliding mode surface are combined to design a prescribed performance global fast terminal sliding mode fault-tolerant controller,which ensures the finite-time stability and transient and steady-state performance constraints of the closed-loop system.Finally,Lyapunov theory is used to prove that the designed controller can make the tracking error asymptotically stable in finite time,and the tracking error satisfies the prescribed transient and steady-state performance constraints.Matlab numerical simulation verifies the superiority and feasibility of the proposed control method.Finally,a double closed-loop adaptive finite-time prescribed performance eventtriggered fault-tolerant controller is designed based on a fixed-threshold eventtriggering strategy for quadrotor UAV with actuator faults,model uncertainties,and external disturbances.The upper bound of lumped perturbations is estimated by using adaptive law for model uncertainty and external perturbations in position and attitude subsystems.The finite-time performance function is combined with the adaptive backstepping control method,and the dynamic surface technique is used to solve the "complexity explosion" problem in the backstepping recursion process,and then the adaptive law is designed to compensate the effect of actuator faults.At the same time,a fixed-threshold event-triggered control strategy is introduced to reduce the controller update frequency.Finally,Lyapunov theory is used to prove that the designed controller can ensure that the tracking error converges to a prescribed neighborhood near the origin in a finite time,and the number of updates is reduced.Numerical simulation verifies the effectiveness of the proposed control scheme.