Research On Control Technology Of Vertical Take-off And Landing Fixed-Wing UAV

VTOL,short for composite wing vertical take-off and landing uav,can be made of simple structure at low cost.At the same time,it can take off and land vertically without runway and fly fast and hover in midair.Therefore,it can be applied widely in industries fields.There is an increasing demand for VTOL,but the control technology of VTOL is lack of research at present.The thesis carries out the research on the control technology of VTOL in the above background.The major work is as follows.Firstly,the thesis describes the typical flight profile of VTOL and divides the flight modes of VTOL into three modes:fixed-wing mode,multi-rotors mode and transition mode.Then the thesis builds 6-DOF rigid body dynamic mathematical models for these three modes according to mass data and aerodynamic data,and the thesis analyzes the aerodynamic characteristics and the modal characteristics.Secondly,the thesis designs flight control system of VTOL.The thesis chooses the hardware for sensor,actuator,and flight control computer.And the thesis explains how to design software.Thirdly,the thesis designs the control law of VTOL in both fixed-wing mode and multi-rotors mode.In the fixed-wing mode,the thesis designs pitch control system,roll control system,height control system,and flight path control system.In the multi-rotors mode,the thesis designs position control system,height control system,course control system,and actuator allocation algorithm.Fourthly,the thesis analyzes the phases in transition mode in detail and designs the control strategies.There's a big uptrend during transition from the multi-rotors mode to the fixed-wing mode,so we take the strategy of elevator feedforward control.And the thesis designs the weight transition scheme for the switchover between the control structure of multi-rotors and that of fixed-wing.There's a big disturbance when the rotor is decreasing,so we take the enhanced control gain.During the transition from fixed-wing mode to the multi-rotors mode,we take the speed command control strategy to make the change of attitude gradual.Due to uncertainty of mathematical model in transition mode,we design a transition experiment to verify control strategy step by step.Finally,with the requirements of shore applications,the thesis designs the control strategy for VTOL to land on a ship on the sea.The control strategy is designed directing at different phases,and the flight experiment is carried out to verify the designed strategy.Then,we analyze the results of the experiment,and the results proved that the control scheme designed is feasible.