Research On Flight Control Of A Small Scale Quad Tilt-Rotor

Since the conventional quad rotor unmanned aerial vehicle(UAV)is limited by the slow flight speed,short battery life and fixed wing aircraft cannot vertical takeoff and landing(VTOL)and hover,a small quad tilt rotor(QTR)UAV was designed in this study.This QTR is tandem wing layout,which has the advantages of fixed wing and multi rotor UAV.The main research contents of this study are summarized as follows:The 3D model of QTR is designed and the corresponding physical prototype is designed.The suitable airfoil for QTR is determined by Profili software,and the lift drag coefficient at different angles of attack is obtained.Then,aerodynamic analysis of tandem wing configuration based on NACA0009 airfoil is carried out by using ANSYS fluid analysis software,and the overall aerodynamic configuration is determined.Based on Catia 3D engineering software,a precise 3D model of QTR is designed and the physical prototype of QTR is manufactured and introduced.According to the characteristics of the actuator of QTR,the basic principle of the realization of its various position and attitude motion is analyzed.Through the analysis of the aerodynamic characteristics and dynamic characteristics of QTR object model,the appropriate coordinate system and the state variables are selected to establish the dynamics and kinematics model of the QTR,which lays a foundation for its control.The control law of the attitude and position tracking of QTR and the control strategy during the tilt transition phase are studied.Overall structure of the control system is given based on QTR's mathematical model;Subsequently,robust servomechanism linear quadratic(RSLQR)optimum control theory is studied,and attitude and position loop control is designed based on RSLQR and PID respectively.Finally,the control strategy for tilting transition stage is discussed.Some digital simulations are designed to verify the controllers.At the same time,in order to get the more vivid simulation effect,the joint simulation of Matlab and FlightGear based on multi platform flight simulator FlightGear software is implemented,which realizes the visualization of the digital simulation.Finally,the actual tests are applied to verified the performance of the QTR prototype.