Fault Tolerance Of Quad-rotor UAV Based On Backstepping Sliding Mode Algorithm Control Research

In recent years,the quad-rotor UAV industry has flourished and played an irreplaceable role in many fields.The quad-rotor UAV has many characteristics like small size,easy operation and simple physical structure.It is widely used in forest fire prevention,agriculture,forestry and plant protection,power line inspection,UAV express delivery,aerial photography,3D modeling,and remote sensing monitoring.etc.The execution tasks of the quad-rotor UAV have become more diversified,making the quad-rotor in a different execution environment,and are greatly affected by factors such as wind direction,geomagnetism,and the UAV’s own actuator,which increase the possibility of failure.Therefore,how to ensure the stability of the flight attitude when the quadrotor actuator fails is an important direction of today’s UAV attitude research.In order to improve the attitude stability of the quad-rotor during flight,and boost the fault-tolerant control capability of the quad-rotor,this paper is based on the fault reconstruction ability of the backstepping control,and because of the sliding mode control’s feedback linearization method.Based on the above two methods,the attitude fault-tolerant controller is designed.Besides,a backstepping sliding mode observer is constructed to observe the failure status of the UAV in real time,and the proposed backstepping sliding mode algorithm is simulated and verified and physical experiments are performed.The specific contents of the study are as follows:(1)First,a dynamic model of the quadrotor UAV is established according to the Newton-Euler equation.Because the quadrotor has the characteristics of nonlinearity and strong coupling,the attitude control of the quadrotor UAV during the flight is a prerequisite to ensure smooth flight.During the flight,the UAV will encounter interference from the surrounding gas environment,or aircraft failure due to the failure of actuators such as motors and propellers.The loss of this failure is expressed as the input loss of each channel,and indirectly expressed as pitch,roll and yaw channel.the fault disturb fault is added to the dynamics equation to established the failure model of the quad-rotor UAV.(2)Secondly,the posture control stability of linear quadratic regulator control,backstepping control,and sliding mode control are compared.Simplified the fault model of the system,the system state variables and input quantities of the quad-rotor system are defined,the state equation of the actuator with additive faults is acquired,and a state observer is established to observe the output of the quad-rotor in real time.The linear quadratic regulator,backstepping controller,and sliding mode controller are established respectively.In the Matlab/Simulink environment,simulation and comparison experiments were carried out under the conditions of no-fault interference and additive fault interference.In the simulation of the Matlab/Simulink environment,it is concluded that the three control algorithms can reach a fast and stable state in a short time under the condition of no fault interference.When there is additive fault interference,the LQR algorithm cannot converge.The SMC algorithm has a small jitter at the initial moment.The motor of the IBC algorithm The attitude control has the phenomenon of jitter.According to the simulation experiments of the above three algorithms,linked with the sliding "mode" characteristics of the sliding mode algorithm and the recursive method of the backstepping method,it can be concluded that backstepping sliding mode control(BSM)is effective for quadrotor UAVs.Strong fault-tolerant controllability.(3)This paper designs an attitude fault-tolerant controller based on the backstepping method and sliding mode method.By constructing the intermediate virtual control quantity,the design of the entire quad-rotor input and output control law is completed,and the backstepping sliding mode attitude fault-tolerant controller is designed,the system parameters are globally optimized,and the weighting matrix is adjusted adaptively,which verifies that the method has better robustness performance,trajectory tracking ability and fault-tolerant controllability.In this paper,through the design of the backstepping sliding mode controller,the simulation comparison test is carried out,and finally the program is programmed for the Pixhawk aircraft,and the field test flight verification is performed.The data obtained by the flight controller airborne MPU6050 module verifies the good trajectory tracking performance and robustness of the BSM algorithm.