基于小波熵的救生伞高速空投最大开伞动载不确定性

针对高速空投试验最大开伞动载测量值离散性大的问题，采用小波熵对试验数据和仿真数据进行对比分析。假人姿态差异大是导致试验测量值重复性差的直接原因，而从空投开始到拉直开伞时刻假人姿态的不确定性是问题的主要来源。试验数据和仿真结果得到的小波熵随空投速度和空投系统质量的变化趋势相同，并且与空投系统的物理本质相符；在考察救生伞开伞动载的试验研究中，仅考虑最大开伞动载的测量值，而忽略系统不确定性是不合理的，因此建议对拉直之前的假人姿态加以控制。

Maximum opening overload uncertainty of high speed airdrop of life-saving parachutes based on wavelet entropy

To solve the discreteness problem of maximum overload measurements in high speed airdrop tests, wavelet entropy is used to compare and analyze the test data and simulation data. Results show that the large attitude difference of the dummy directly causes the poor repeatability of test measurements, while the attitude uncertainty of the dummy from the start of the airdrop to the parachute straightening moment is the main source of the problem. The wavelet entropy obtained from the experimental data and simulation results is consistent with the physical nature of the airdrop system, exhibiting the same variation trend as that of the airdrop speed and the airdrop system mass. Therefore, it is unreasonable to consider only the measurement value of the maximum overload and ignore the system uncertainty in the experimental study of the life-saving parachute open load. Hence, it is suggested to control the dummy posture before straightening of the parachute.