起落架四点布局无人机着陆动力学分析

The dynamic analysis of UAV with four wheels landing

以起落架四点布局无人机为研究对象,基于理论力学、刚体动力学、多体系统动力学及轮胎动力学基础理论,在MATLAB/SIMULINK中建立包含飞机六自由度运动、4组起落架缓冲器运动、轮胎偏转、气动力的起落架四点布局无人机着陆的动力学模型。对飞机不同姿态着陆工况进行仿真,结果表明:模型能够精准反映飞机着陆动力学特性;相对于水平着陆,俯仰角为正时飞机质心过载减小,主起轮胎载荷明显增大且最大值出现时间后移;存在滚转角着陆时,起落架四点布局飞机先接地一侧前起能够吸收部分能量,有效减小主起落架着陆过程中的冲击载荷;随滚转角增加先接地一侧轮胎载荷缓慢增加,后接地一侧轮胎载荷显著减小;且随着滚转角增大,后接地一侧起落架吸收能量减小,其中前起吸收能量的减小量多于主起。

This paper concentrates on a UVA with four wheels , establishes the dynamical model of UVA landing movement based on theoretical mechanics , dynamics of rigid body , dynamics of multi-body systems and basic dynamic theory of tire .This model contains six -degrees -of -freedom aircraft body, four groups of buffer movement , tire deflection and aerodynamic force in Matlab/Simulink .Simulations of different attitude landing show that：the model can accurately reflects the aircraft landing dynamics;relative to horizontal landing , the o-verload of aircraft centroid decreases and loads of main tires increase obviously with positive pitch angles , the maximum loads of main tires delays;Landing with a roll angle , the early-touchdown nose landing gear of the UVA with four wheels can absorb a part of energy , reduce the impact loads of main landing gear effectively . With roll angle increasing ,the loads of early-touchdown tires increase slowly , and the loads of late-touchdown tires decrease obviously .With roll angle increasing , the absorption energy of late -touchdown nose landing gear decreases more obviously than that of main landing gear .