Research On Fault Diagnosis For UAVs Formation Systems Based On Observer

In recent decades,with the rapid development of aeronautics technology,many countries have paid more and more attention to the development of UAV technology.Meanwhile,the research on UAV technology is becoming more and more concerned.In the existing technology,although the UAV technology has developed mature relatively,the UAVs formation flight technology still has great development and research space.Because of the complexity and high security requirements of UAVs formation system,fault diagnosis is particularly important.This paper studies the leader-follower distributed UAVs formation system,and the methods of unknown input observer and sliding mode observer are applied to diagnose faults when single actuator,single sensor,multi-actuator,multi-sensor and communication topology fail.This research mainly includes the following contents and innovation.1.For a class of distributed formation flight system with actuator faults,a distributed fault diagnosis method based on unknown input observer is proposed when the input information is unknown.Firstly,the method of ascending order is used,and the new state is introduced by combinating a former state and actuator fault vector,which makes the external of interference distributed formation system decouple.Then the fault of the system is determined by using the method of unknown input observer,and a set of gain matrix about UAVs formation distributed fault diagnosis observer is obtained,which combines fault in augmented system.Finally,the fault estimation is obtained.2.When actuator fault and sensor fault occur simultaneously in single UAV,a fault diagnosis method based on sliding mode observer is proposed to solve the problem of fault diagnosis of UAVs formation system.First of all,the fault model needs to be processed.A new state variable is introduced,the sensor fault is equivalent to the "pseudo actuator fault",then "the total actuator fault" of UAVs formation system is diagnosed.The residual signal of sliding mode observer and output of "the total actuator fault" are used to diagnose fault,the proposed fault diagnosis method based on sliding mode observer is applied to ensure the stability of sliding mode observer.3.An active fault tolerance method based on sliding mode observer and transformed generalized observer is proposed to solve the fault diagnosis problem of the UAVs formation system in the case of actuator,sensor and communication topology faults.Firstly,the control law of formation is designed to ensure the stability of the forward distance corresponding to velocity,the lateral distance corresponding to acceleration and height,thus ensuring the stability of the whole UAVs formation.Secondly,control law among single UAV is designed to track the speed and acceleration signals of the external formation.Then,when the actuator,sensor and communication topology faults occur,sliding mode observer and transformed generalized observer are used to estimate the actuator,sensor and communication topology faults.Finally,the validity and feasibility of the fault diagnosis are verified by the simulation method.