Research On Flight Control Of Tilt-rotor UAV

Tilt-rotor UAV is a new type of unmanned aerial vehicle. It has both flight characteristics of helicopter and fixed wing aircraft. When tilt-rotor UAV flies in helicopter mode, two rotors provide main lift, so the aricraft can hover or fly at low speed. After rotor nacelles tilt to horizontal position and provide forward force, the aircraft becomes airplane at high speed, with lift provided by wings. This thesis aims at studying the flight dynamics characteristics of tilt-rotor uav in helicopter mode, transition mode and fixed wing mode, through establishing a mathematic model of tilt-rotor uav, then designing flight control system and carry on simulation experiment. The specific work is as follows.1, The aerodynamic force and torque calculation of every parts of the aircraft is studied respectively by component method, and the rotor-wing aerodynamic interference is considered. Then a tilt-rotor UAV mathematic model is established and a graphical flight simulation model is established in Matlab/Simulink environment for trim analysis and control system simulation.2, Longitudinal trim analysis of the aircraft is performed to analyze their motion characteristics and handling characteristics. Then, the control efficiency of the two sets of rotor and aero-rudder control system in mode conversion process is analyzed to design the manipulate strategies. Then some feature points is chosen to study aircraft dynamics characteristics during the transition through establishing of a linear state-space equation and eigenvalue analysis with the small perturbation hypothesis.3, The tilt-rotor UAV flight control system is designed, including pitch angle control systems, speed control systems, vertical speed control systems, altitude control system in longitudinal channel, and roll angle control system, side-slip angle control system, heading control systems in latitude channel. The control system structure and feedback parameters is designed by the classical control theory root locus analysis and frequency response analysis.4, In Matlab/Simulink simulation environment, numerical integration of comprehensive equations of motion is performed by fourth-order Runge-Kutta method. Effectivity of the control system are tested by climbing, altitude holding, heading conversion in cruise flight with gust interference.