| Vertical takeoff and landing UAV is a new type of UAV in recent years,including hybrid,tiltrotor,tailsitter and other types,each type has its own advantages.The structure of Hybrid VTOL(vertical takeoff and landing)UAV,a typical kind of UAV,is simple and easy to operate,and it has most of the advantages of multi-rotor UAV and fixed-wing UAV.It can take off and landing vertically in multi-rotor state and hover,as well as high-speed flight and large-scale cruise in fixed-wing state.Hybrid VTOL UAV has been gradually developed and used in power patrol,plant protection,topography survey and other industries.The flight transition from multi-rotor to fixed-wing is the key to realize these advantages for hybrid VTOL UAVThis article aims to study on the control algorithm of hybrid VTOL UAV in flight transition based on PX4 flight control system.Firstly,this article introduces the research background and significance of hybrid VTOL UAV,domestic and foreign development status and the main research contents of this article.Then the assembly and system composition of hybrid VTOL UAV are described.The flight principle of hybrid VTOL is described in detail,which is divided into two independent flight states:multi-rotor state and fixed-wing state.The safety inspection and setup before flight test are described,and the flight test is completed.Then the structure framework of PX4 flight control system is analyzed,including PX4 construction and program compilation method,uORB message mechanism,flight control stack,position control algorithm,attitude control algorithm and manual,assisted and automatic flight modes.Then the control ratio of multi-rotor and fixed-wing in transition state is controlled by the square of flight speed,and the tanh(x)function is used to the attitude and position controller of multi-rotor to control the output range.Then the relationship between the Gazebo and PX4 is introduced.Finally,the flight test verified by simulation with Gazebo,and the flight data graphs are analyzed. |
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