Fault Tolerant Control Aiming At UAV Damage

The wide application of high-value UAVs in the military field makes it inevitably a key target of the enemy.Under harsh combat environments such as electromagnetic interference and firepower strikes,the reliability and survivability of UAVs have become an important guarantee for the completion of combat missions.In order to improve the survivability of high-value UAVs after failure and aerodynamic damage,this paper mainly conducts research from two aspects: when the sensors fail or are damaged,the reliability of the flight mission is ensured through the configuration and management of component redundancy.When the UAV is aerodynamically damaged,its flight state will deviate significantly in a short period of time.Fault-tolerant control methods are used to restore the flight state as much as possible under the current conditions.The main contents of the study are as follows:(1)Design of redundancy fault-tolerant system for sensors.Aiming at the problem of poor fault tolerance of UAV’s single-redundancy sensor,a set of four-redundancy sensor redundancy fault-tolerant system architecture and management process is proposed,so that UAV can retain its information perception ability under failure or damage conditions.Aiming at the problem of complex redundancy system algorithm,a set of redundancy management algorithm with clear logic and high fault tolerance is designed to improve the reliability and stability of the system.By constructing the monitor,voter,and fault recovery modules in the redundancy management algorithm,it can effectively identify and isolate various fault signals such as open circuit,pulse,and saturated output,and can restore transient faults,avoiding the waste of system resources caused by "false alarms".The above-mentioned redundancy management system was built under Simulink environment,and its reliability was verified by simulation.The designed redundancy management system is also suitable for the voting judgment of the executive agency’s control law.(2)Dynamic analysis of UAV with aerodynamic damaged.Aiming at the problem of the change of UAV model parameters after aerodynamic damage,a dynamic analysis of the aerodynamic damage UAV is carried out.The aerodynamic damage of the UAV will cause its center of mass,moment of inertia and other dynamic parameters to change.The traditional UAV dynamic model cannot meet the research needs.Based on the establishment of the normal UAV dynamics model,this paper takes the center of mass of the normal UAV as the reference point,and considers the parameter changes caused by the aerodynamic damage such as the offset of the center of mass,the 6-DOF dynamics of the aerodynamic damaged UAV is derived and established.The shape of the damaged UAV is modeled in three dimensions using CATIA software,and the center of mass and moment of inertia are estimated.The aerodynamic parameters of the UAV are simulated and calculated using FLUENT software.The dynamic characteristics caused by the damage are analyzed.(3)Reconfiguration design of control system for UAV with aerodynamic damage.Aiming at the problem that the UAV cannot maintain normal flight after aerodynamic damage,combined with PD control and L1 control,the UAV fault-tolerant control system design was completed,and linear model simulation and six-degree-of-freedom nonlinearity under different damage conditions were carried out.The results show that within a certain degree of damage,the flight control system reconstruction scheme based on the L1 control method can adapt to the model parameter changes caused by the damage and effectively suppress the deterioration of the UAV flight status.Compared with the PD control method,it solves the problem of stable flight after the wing damage to a greater extent,and improves the reliability and survivability of the UAV.