Research On Segmentation Control Strategy Of A Uav Fixed-wing

Vertical take-off and landing(VTOL)fixed-wing UAVs combine the advantages of the traditional fixed-wing UAV and rotorcraft.It has the characteristics of vertical take-off and landing,hovering and low-speed cruising of the rotorcraft and high-speed cruising of the fixed-wing UAV at the same time,which makes the VTOL fixed-wing UAV can be deployed in complex geographical conditions and missions requirement higher occasions.The unique functions of VTOL fixed-wing UAVs have drawn wide attention and research from domestic to foreign institutions and scholars.This paper mainly research the design of the flight controller of the VTOL fixed-wing UAVs.VTOL fixed-wing UAVs have seven flight status including take-off,climb,fly,drop,pull hover,inverted slip,hover and soft landing.The above seven flight states can be summarized as horizontal flight mode,vertical flight mode and transitional flight mode.Due to space limitations,this article only designs controller for the UAV vertical flight mode.To this end,this article describes and analyzes the UAV model mathematically.First of all,the mathematical model of UAV is established and the vertical flight ground coordinate system and the horizontal flight ground coordinate system are introduced for the Euler angle singularity under the UAV vertical flight state.At the same time,the quaternion method of full attitude solution is introduced to solve the Euler angle singularity problem.The formation mechanism of UAV force and moment is analyzed,and then the nonlinear six-degree-of-freedom mathematical model of UAV is deduced by Newton's law and momentum moment theorem.Then,in order to facilitate the design of the flight control system,reasonable assumption is made during the inversion slip phase,which simplifies the mathematical model of the UAV.A small perturbation linearization of the nonlinear model is performed near the working point,making UAV decoupling linearization of the mathematical model.In the hovering soft landing phase,the quaternion equation is used to describe the attitude,and the linear decoupling method is also adopted to make the attitude and velocity and high decoupled.During the vertical take-off and landing phase,the UAV is equivalent to the unstable inverted pendulum,which has a serious non-linearity.In this paper,the attitude control law of hovering soft landing is designed by means of feedback linearization.The controller of the design is simulated respectively to verify the performance of the control system.Finally,summarize the major work done in this paper,and pointed out the deficiencies according to the existing work,put forward the requirements for the next step.