大型降落伞抽打现象的录像分析方法

摘要

The paper presents a method for analysis of large parachute＇s bullwhip phenomenon based on a single camera＇s video image processing.Firstly,the deployed parachute＇s axis is obtained as connected lines,and the canopy＇s shape and location could be calculated according to the parachute＇s geometry.And then,the applicability of the method is proved by a parachute model measurement and a simple pendulum＇s video measurement.Finally,the numerical results of two different flight-test videos,with or without bullwhip phenomenon are given.The comparison shows that when bullwhip occurres,the canopy would get a higher frequency,longer swing,and the mean velocity between two consecutive frames of the canopy＇s apex is faster.The conclusion was helpful for theoretical research.%文章提出一种利用单台无姿态信息摄像机拍摄的空投录像来分析大型降落伞抽打现象的方法,利用图像处理方法得到拉直结束后降落伞中轴线,并将之近似为相互连接的直线段,并以降落伞结构参数作为先验信息求解拉直结束后伞衣位形,同时采用静态测量及单摆试验测量方法验证了分析方法的有效性,最后对有无抽打现象产生两段大型伞空投试验录像进行分析。分析表明,抽打发生时,伞衣顶部摆动剧烈,持续时间长,两帧间平均速度较大,分析结果可为抽打现象的理论研究提供数据验证。