STOVL Unmanned Aerial Vehicle Flight Dynamic Analysis?Control Law Design And Test

This paper takes two different configurations of STOVL(short take-off vertical landing)UAV(unmanned aerial vehicle)with thrust vector and tilt-rotor as objects of research,the flight dynamic model/flight quality/flight performance/flight control design/ground effect problems are explored,new modeling,design and analysis methods based on multi-discipline research and application are developed and established.Flight dynamic modeling is the premise of flight quality performance analysis and flight control law design,in order to obtain the required aerodynamic data of flight dynamic modeling,scaled models of thrust vector and tri tilt-rotor STOVL UAV are used in wind tunnel tests,a unified platform is builded for flight dynamic model using MATLAB/JSBSIM software.Combining with such as the propulsion system,rudder dynamic characteristic data of aircrafts,six degrees of freedom nonlinear dynamic models of thrust vector and tri tilt-rotor STOVL UAV are established based on this platform.In order to design the special flight guidance and control law of thrust vector STOVL UAV,including short takeoff,routine flight,deceleration transition and vertical landing,some flight qualities in transition and hover states are analyzed and calculated,as well as short take-off performance,deceleration transition performance,level performance and maneuverability performance of thrust vector STOVL UAV,then the precise flight control strategy is formulated.According to the control strategy and requirements of each flight phase,the corresponding outer loop guidance systems and inner loop control systems of thrust vector STOVL UAV are established;the total energy control and implicit dynamic inversion methods are adopted in outer guidance systems based on flight guidance policy of different phases,the improved eigen-structure assignment method is used in inner loop control systems.Based on flight dynamic model of thrust vector STOVL UAV,these methods are verified through linear simulation and six degrees of freedom nonlinear flight dynamics virtual flight simulation.The said methods are applied on flight control system design of tri tilt-rotor configured STOVL UAV,and then verified through semi-physical flight simulation and flight test.The results show that,the total energy control guidance has better decouple and coordination control of flight trajectory and speed in conventional flight phase,the integrated design method based on implicit dynamic inversion and improved eigen-structure assignment has physical unambiguously and can configures inner and outer loop dynamic characteristics directly,it can be used for rapid assessment of deceleration transiton and vertical landing program.Based on the ground effect problem of STOVL,this paper takes the tri tilt-rotor STOVL UAV for example.In order to explore the issues of forces on the aircraft airframe and characteristics of flow field under aircraft body in hover and low speed forward flight states within a certain height from ground,a comprehensive experimental program is designed in low speed wind tunnel.The conditions of forces on the aircraft airframe and characteristics of flow field under aircraft body are obtained by ground effect experiment,the significant uploads and fountain flow effects are observed.Experiment results verify that the less power consumption hovering near ground.The experimental scheme provides a reference for future research of ground effect about similar STOVL aircraft.The flight dynamics modeling,flight strategy development,control system design,flight test and ground effect experiment of STOVL UAV in this paper provide certain theoretical and engineering reference value for domestic STOVL aircraft design and development.