Research On Fault-Tolerant And Secure Variable-Structure Control For Quadrotor Systems

With the development of science and technology,quadrotors have gradually been applied to civil field,military field,scientific research and many other fields.It brings convenience to people’s lives with its lightness and simple operation.It provides new ideas for combat strategy with its compactness and high flexibility.It provides new topics for scientific research with its non-linear and under-actuated characteristics.However,the application and popularization of quadrotors have also brought many new problems.For example,the aging of components and improper operation by the user may cause the quadrotor to malfunction or even cause injuries.At the same time,the open communication environment of quadrotors provides opportunities for criminals.Loss of control or crash of the quadrotor under a malicious attack may cause property damage and casualties.Therefore,the problem of fault and security of quadrotor systems is an important subject.This paper uses the rotation matrix method to construct the dynamic model of the quadrotor.Based on the structural characteristics of the quadrotor and the problems it faces,the followings are the specific research work carried out in this paper.(1)The design of an adaptive variable-structure controller for quadrotor is studied.Based on the analysis of the control structure of the quadrotor,the quadrotor system is divided into an attitude inner loop and a position outer loop,and an adaptive observer is constructed to estimate the interference caused by uncertainty on the attitude loop.At the same time,by combining the analysis methods of backstepping and variablestructure control,the control law on each channel is derived,and the stability of the control system is proved by Lyapunov’s method.(2)The fault-tolerant control of the quadrotor under the multiplicative faults of the actuator(motor)is studied.By defining the total disturbance of the system,the multiplicative faults and normal disturbances are regarded as a single variable.The mathematical model of quadrotor under the multiplicative faults of the actuators is constructed,and the finite-time ESO(Extended State Observer)is designed to estimate the total disturbances.At the same time,the total disturbance compensation is performed on the backstepping variable-structure controller to realize the fault-tolerant control of the quadrotor.(3)The strategy for secure flight of quadrotor under FDI(False Data Injection)attacks is studied.By analyzing the FDI attack in the trajectory command signal,the strategy for secure flight of quadrotor is given,and the similarities and differences between FDI attacks and actuator faults are compared.At the same time,a robust adaptive observer based on LMI for the ground station is designed,and the mathematical relationship between the control input increment and the attack signal under the backstepping variable-structure control is analyzed.Finally,the attack signal compensation is performed on the trajectory command signal to ensure the secure flight.(4)Simulation experiments are carried out for the above research,and the simulation results under different flight missions are given,which proves the effectiveness of the theory in this paper.