Research On Redundant Flight Control System Of Flying Wing Unmanned Aerial Vehicle

As flying wing UAV adopts blended wing body design and tailless layout,giving it the advantages of light weight structure,large effective lifting surface,small flying resistance and high stealth characteristics.However,due to the cancellation of horizontal and vertical tails,the UAV's lateral and longitudinal stability characteristics are deteriorated,and need to take new control strategies.In order to improve the reliability of long-haul flight,a redundant flight control system was introduced.Firstly,dynamic modelling and control law design for a certain type of flying wing UAV were carried out based on the mass database and aerodynamic database.On the basis of the conventional layout fixed-wing control laws as well as the operational stability analysis results,the angle-of-attack feedback control was added to the vertical control loop.In addition,the longitudinal damping of the system is increased to improve the longitudinal stability of the flying wing UAV.As for lateral control,the crabbed method was used to control the rudder in order to solve the sideslip caused by crosswind,so as to improve the azimuth stability of the UAV.A flight test was performed with a scaled model UAV to demonstrate the feasibility of the control strategy.Secondly,from the perspective of enhancing the safety and reliability of the flying wing UAV,considering the difficulty of engineering implementation,size constraints,costs and other factors,an integrated redundant flight control system architecture were designed.According to the software communication flow,the redundancy management software design and application software design based on FlexRay bus are also completed.A semi-physical flight simulation platform based on a flying wing model was set up for simulation experiments.The simulation results showed that the integrated redundancy flight control system based on FlexRay bus can effectively improve the flight reliability.Finally,due to the limitation of the effective communication distance of the FlexRay bus(24 meters),this paper proposes a solution to extend the communication distance by replacing the FlexRay physical layer with the RS-485 physical layer.Key technologies of electromagnetic interference and transmission cable selection,which affect the quality of bus communication,were studied.This paper completes the design of hardware circuit,and successfully finishes the synchronous communication tests between nodes.