飞机过度/不足转向地面转弯操纵特性分析

Analysis of oversteer/understeer characteristics of aircraft ground steering

为分析飞机着陆滑跑过程中的过度/不足转向特性,提高前轮转弯系统的操纵性能,提出了一种具有时变参数的飞机转弯系统的低阶等价模型,并结合系统稳定性的分析与飞行数据,可知在飞机着陆滑跑过程中的某个速度范围内,由于系统偏航角速度命令带宽衰减至零值附近,飞机的过度/不足转向特性曲线十分接近临界稳定速度边界,引起操纵特性严重恶化,由此提出了一种采用偏航角速度的局部负反馈来调节系统带宽的自校正增稳设计.分析与仿真结果说明:该模型能够解决使用高阶模型对飞机该项性能分析复杂的问题,可以作为高阶复杂模型分析的一种补充,且提出的增稳方法能使系统偏航角速度命令带宽保持在期望范围内,改善脚蹬操纵的敏感性,提高系统的操纵性能.

A lower-order equivalent aircraft steering system model with time-varying parameters was developed to analyze oversteer/understeer characteristics of aircraft steering and improve handling characteristics of nose wheel steering system after touchdown.Combining system stability analysis with flight data,it is found that the curve of oversteer/understeer characteristics rapidly approaches to the critical speed stability boundary in a certain speed range,which is caused by yaw rate command bandwidth decreasing nearly to zero.It results in a sharp deterioration in ground-handling characteristics.Then a stability augmentation design with self-tuning controllers was proposed,using a yaw-rate feedback as the cue of adjusting.The analysis and simulation indicate that the model proposed simplifies the related analysis which would be a complex problem in high-order models and it could be used as a complement to high-order,detailed model analysis.And the stability augmentation design could set yaw rate command bandwidth in a desired range and ameliorate the rudder pedal sensitivity,greatly improving the ground-handling characteristics.