Research On Flight Mode Conversion Control Method Of The Lift Converted UAV

The lift converted unmanned aerial vehicle(UAV)is a novel structure and powered by ducted propeller,which not only have the abilities of vertical takeoff and landing,hovering as a helicopter,but also can cruise with high-speed as a fixed-wing.Flight mode conversion is one of the most important parts of all flight modes forlift converted UAVs and it is a bridge from hovering toforward flight ata high-speed.Since the transition mode of lift converted UAV is a large maneuver and the aircraft is a highly nonlinear MIMO system thatchallenges the designingof flightcontrolsystem.In this paper,the control method fortransition modeis studied and researched based on the modelaircraft designed by the laboratory,flight tests show the feasibility of the model aircraft and has laid a foundation forthe transition mode control technology of lift converted UAVs in the future.Firstly,by the introduction of the structure for lift converted UAVs,a six-degree-of-freedom(6 DOF)nonlinear mathematical model of the lift converted UAV is established by adopting the modular modeling idea and validated in MATLAB.Then,the stabilities of lift converted UAV is analyzed.It is laid a foundation for the establishment of transitional corridors and the design of control law.Secondly,the maneuvering strategy during the transitional mode is studied and the initial transition conditions are analyzed in detail,then the transition flight corridor is obtained.In order to facilitate the study of the transition section,the 6-DOF model of the aircraft is simplified and the longitudinal model of the transition section is obtained.On this basis,the designing and simulating of the control law for longitudinal stability control,pitch angle tracking control,flight speed tracking control and the whole transition process are carried out in all flight states.Thirdly,considering the transitional mode of the aircraft is a large maneuver and the aerodynamic parameters change greatly as well as unpredictable disturbing factors,an1 L adaptive tracking control method for the transitional flight is proposed,which has better tracking control effect and robustness than the conventional controller.The feasibility of1 L adaptive tracking control method in the transitionalmode of the aircraftis demonstrated by simulation experiments.Finally,a dual-core controllercomposed of DSP and ARM is designed and the actuators and sensor systems are selected for the whole flight test.The flight control algorithm software and remote telemetry system software development and implementation.The flight experiments demonstratethe correctness of the control law for transitional mode and the reliability for the flight control system.