Research On Fault Diagnosis Expert System And Fault Tolerant Control Technology For Low Altitude Unmanned Airship

The low altitude unmanned airship is a lighter-than-air aircraft which possesses lower energy consumption and manufacturing costs compared to other aircrafts,so it has high utilization value in both military and civilian fields.Due to the special working environment,the long-term operation may cause the airship system and internal components to malfunction such as aging and drift,which may cause economic and even personnel damage.In the traditional low altitude unmanned airships,fault diagnosis and fault-tolerant control have problems such as low diagnostic efficiency and limited fault tolerance.Under the above background,the paper makes further research on the fault diagnosis of low altitude unmanned airships and fault-tolerant control under faults.Firstly,based on the low altitude unmanned airship structure layout and dynamics model,the paper analyzes its flight characteristics and control principle.According to the knowledge of the diagnostic expert,the faults are classified,and the fault tree has been established according to the causal relationship.Then,the fact base and rule base are designed based on the CLIPS expert system framework,and the corresponding data exchange interface and human-computer interaction interface are designed.Secondly,in order to improve the stability of the low altitude unmanned airship,the paper broadens the output error vector to the original state space model.The LQR fundamental controller is designed for the longitudinal and lateral motion models respectively.The simulation results illustrate the effectiveness of the controller.Finally,the reconfigurability of the low altitude unmanned airship is analyzed for the problem of the actuator failure.Then,the general model of the actuator-input encountered with different faults has been established.The fault-tolerant reconfiguration controller under different fault modes is designed by pseudo-inverse method,which realizes the reconfiguration of the original control commands to other effective operating mechanisms.The simulation verifies the effectiveness and reliability of the fault-tolerant control strategy.In summary,the paper studies the fault diagnosis and fault-tolerant control of unmanned airships working at low altitudes.The fault diagnosis expert system is designed and developed,and based on its control redundancy,a fault-tolerant reconstruction controller based on pseudo-inverse method is proposed,which is of great significance for the safety and reliability of unmanned airships.