Research And Design Of Flight Control System For Tilting Multi-rotor Unmanned Aerial Vehicle

Tilting quad-rotor unmanned aerial vehicle(uav)has high flight efficiency,large capacity,the characteristics of good maneuverability.And it can combine the advantages of fixed-wing uav and multi-rotor uav.The UAV can perform vertical take-off and landing stabilization,hover in the air,smooth transition of the pod,and smooth flight at high speed.However,in the transitional flight mode,the flight controller design is more complicated.Therefore,this paper designs a tilting quad-rotor unmanned aerial vehicle which was taken as the research object,and its modeling was carried out.Then it study the design of flight controller in transition flight mode.Finally,the flight control law designed in this paper was verified through Simulink and FlightGear co-simulation and flight test.Firstly,the aerodynamic model of the tilting quad-rotor uav was built by selecting the appropriate wing and tail shape as well as the fuselage.The aerodynamic model was analyzed by ICEM CFD software and Ansys Fluent software to obtain the relevant aerodynamic coefficients of the wing,tail,fuselage,steering engine and other components.The aerodynamic coefficients are fitted to the curves of the Angle of attack or sideslip,which are used to calculate the aerodynamic forces in the dynamic model of the UAV.Secondly,matlab/ Simulink software was used to build the dynamic model of the tilting quadrotor UAV,which was used to obtain the transfer function of each channel of the UAV as the controlled object in the subsequent flight control law design.Tilting quad-rotor uav has three flight modes: fixed wing flight mode,helicopter flight mode and transition flight mode.Therefore,the three flight modes need to be modeled separately.In addition,in the fixed wing mode and transition mode,the difference between the v-tail and the tail which is the normal layout should be considered to conduct the control characteristics and force analysis.And the research on the tilting corridor ensures that the transition flight mode can be switched smoothly under certain conditions.Then,the flight control law is designed for every flight mode.Based on the idea of scheduling gain,the strategy in the transiton flight mode is that using the weight integrate the flight control law of rotor flight mode and the fixed-wing flight mode.PIDcontrol is adopted as the flight controller of the fixed wing flight mode and helicopter flight mode.Through the analysis of the bode diagram of the control loop,the system performance of the flight control loop is obtained,and necessary correction steps are taken to make the designed flight control loop meet the response performance required by the system.It complete the determination of the weight,and design the cabin tilting control loop.Finally,the flight control law of the tilt-rotor UAV is verified by Simulink and FlightGear joint simulation.Then by analyzing the simulation curve and flight data,the rationality and feasibility of the flight control law design are verified.