Research On Design And Control System Of Multiple Flight Mode Vertical Take-off And Landing UAV

Vertical take-off and landing UAV has the advantages of fast cruise speed and long flight time,it can also take off and land vertically in the air,which can realize the task of integrated implementation of complex application scenarios.Tail seat vertical take-off and landing UAV belongs to a kind of vertical take-off and landing UAV,which has the advantages of simple mechanical structure,no redundant mechanism,relatively simple control algorithm and strong reliability,it has attracted much attention in the military and civil fields.At present,the research of tail seat vertical take-off and landing UAV mainly focuses on the structural design of UAV,the research on control theory is less,the attitude control accuracy of UAV during hovering is low,and the wind resistance is poor.The technical difficulties such as unstable flight mode conversion have not been completely solved,which restricts the popularization and application of vertical take-off and landing UAV.In order to solve the above problems,a tail seat vertical take-off and landing UAV is designed in this paper.the tail seat vertical take-off and landing UAV is optimized and improved from two aspects of structure design and control algorithm.The main research work is as follows:In order to improve the flight efficiency and flight quality of the tail seat vertical take-off and landing UAV,the structure of the tail seat vertical take-off and landing UAV is analyzed and designed theoretically.From the aspects of wing load,power to weight ratio,wing,power system,take-off weight and so on,the selection and parameter selection of UAV system are analyzed in detail,and the system parameters of UAV are put forward.On this basis,the coordinate system of the tail seat vertical take-off and landing UAV is established,and the six-degree-of-freedom nonlinear mathematical model of the UAV is established based on the kinematics and dynamics equations.In order to solve the problems of low attitude control accuracy and easy wind disturbance of tail seat vertical take-off and landing UAV in hovering mode,an active disturbance rejection control method is proposed to control the position and attitude of UAV during hovering.Firstly,the motion principle of UAV in hovering mode is analyzed in detail,and the PID controller and ADRC are designed.the control effects of PID controller and ADRC are compared by simulation experiments.It is proved that the ADRC improves the control accuracy and robustness of the tail seat vertical take-off and landing UAV system.In order to solve the problems of slow transition speed and unstable altitude change of tail seat vertical take-off and landing UAV,the flight control strategy of UAV transition mode is deeply studied.An innovative control strategy for determining the height of the fastest mode conversion is proposed.The flight effects of classical PID control strategy,fastest mode conversion control strategy and fastest mode conversion fixed height control strategy are analyzed and compared by simulation experiments.The proposed fastest mode conversion height determination strategy optimizes the two flight parameters of conversion speed and altitude change,and maintains the force balance in the vertical direction of UAV in the process of mode conversion.The experimental results show that the proposed fastest mode conversion fixed height control strategy solves the problem of height drop in the tail seat vertical take-off and landing UAV mode conversion,and can ensure the UAV to realize the flight mode conversion quickly and smoothly in the transition mode.Finally,the prototype of the experimental principle is built and the actual flight test is carried out.The control accuracy of pitch angle and roll angle of the tail seat vertical take-off and landing UAV can reach ±3 °,the control accuracy of yaw angle can reach ±5 °,the flight mode conversion time is 2.3 s,and the maximum height change is 1.5 m during the conversion process.Test junction.The results show that the UAV has the characteristics of high hovering attitude control accuracy,strong wind resistance,and little change in the height of the conversion flight process.