Design And Implementation Of A Tilt Rotor Unmanned Aerial Vehicle Flight Control System

In the 20 th century,the technology developing rapidly in the field of unmanned aerial vehicle(UAV),the technology of vertical take-off and landing and autonomous ship landing have a more rapid development in recent years.Tilt rotor UAV is a kind of VTOL UAV with the characteristics of rotor aircraft and fixed-wing aircraft,it has three flight modes: rotor flight mode,tilt flight mode,fixed wing flight mode.But how to control the attitude of in tilt flight mode is the key problem.In this paper,the tri-tilt rotor UAV is the research object,mathematical model is build in view of the tilt rotor's control scheme and structure configuration.Parameters in the mathematical model is measured by several designed experiments.Then,problem in attitude control in tilt flight mode and rotor flight mode were studied.Attitude controller and control allocation are designed based on the flight characteristics of rotor flight mode and fixed wing flight mode.Tilt strategy is also designed based on the difference between flight modes.Main work and innovation points are as follows:(1)The layout and control scheme of the tilt rotor UAV in rotor flight mode have been studied.There are many types of structure configurations,in this paper,configuration of platform is designed by comparing several kinds of advanced VTOL UAV.The goal is to design a VTOL UAV which has high-efficiency power system and lower air resistance.The design of power system and its parameters are decided by several designed experiments.(2)The six degrees of freedom nonlinear model of the tilt rotor is established.Additional force and moment which added on tilt rotor in rotor flight mode are analyzed,mainly including the force and moment produced by rotor,resulting from installation wing aerodynamic and resulting from rotor rotated tilting torque,etc.The inertia moment of the aircraft have measured through several experiments which lay a solid foundation of designing attitude controller.(3)Different attitude controllers have been designed to use for different flight mode.The control schemes have been changed due to the difference between flight modes.In this paper,different attitude controllers have been designed to guarantee the stability of the attitude of the tilt rotor in different flight modes.Finally,the feasibility,robustness and reliability of the designed attitude controller is verified by flight tests.(4)Tilt strategy in take-off phase has been designed.The acceleration performance of tilt rotor in rotor flight mode is weak.The demand of tilt rotor's flight speed is high in fixed wing flight mode.This paper put forward to a tilt strategy according to the different additional force and additional moment between two flight modes.(5)Tilt strategy in landing phase has been designed.The acceleration performance of tilt rotor in fixed wing flight mode is efficient,but hovering and vertical motion is the basic motion in rotor flight mode.In this paper,the tilt strategy in landing phase is designed based on the characteristics of two kinds of flight modes.Finally,the feasibility,robustness and reliability of the designed tilt strategy is verified by flight tests.