软着陆气囊缓冲特性与参数设置的理论研究

Cushioning characteristic and parameter design of a soft landing airbag

将软着陆气囊的缓冲过程分解为绝热压缩和排气释能两个过程,从热力学和刚体动力学的基本方程出发,建立了软着陆缓冲过程的理论分析模型,并给出了缓冲响应的数值计算方法。针对立式软着陆气囊的参数设置和缓冲响应估计问题,给出了固定排气口型气囊和可控排气口型气囊相关参数的设计方法,同时以一个无人机模型的软着陆回收为例进行了缓冲响应仿真。基于简化模型及缓冲过程状态参数-时间特性曲线,分析研究了未设置排气口、固定型排气口与可控型排气口气囊的缓冲特性及其应用优劣,为工程与研究人员提供了气囊尺寸估算、缓冲系统性能预测、排气口面积选择与主动控制律设计的理论依据,研究结果具有明确的工程参考价值。

A normal soft landing process with a gas-filled bag can be decomposed into two physical stages: the first one is an adiabatic compression of airbag, then the second one is a release of landing shock energy. Based on thermal dynamic and rigid dynamic equations, the analytical model of a soft landing airbag was developed, thus a simple and quick numerical solving method for cushioning response was presented. As an example, the parameter determination method for a vertical cylinder soft landing airbag of an unmanned aircraft was proposed, and the parameters included the height of the airbag, the bottom area of the airbag and the area of the vent orifices. The cushioning time histories of the soft landing airbags with different types of vent orifices including no gas bleed, constant-area orifices and controllable orifices were calculated by a Matlab program. Compraring these simulation results, the advantages and disadvantages of different soft landing airbags were concluded, and some improvement advice on design of a soft landing airbag was proposed.