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过去在进行测量设备精密度及准确度的综合估算时,均将子样均值及子样方差作为母体均值及母体方差。这样做往往把精确度估计过高,造成虚假精确度。近年来,国内外的一些作者都在其文章中引入了置信度、不确定度、极限误差等概念。但不确定度和极限误差都与自由度有关,而不同误差源的自由度并不一定相同。故“平方相加开方求综合极限误差”的方法只适用于各误差源的自由度都相同的情况。本文提出了不同自由度极限误差及不确定度的综合公式。如果测量设备经过了校准,则其系统误差是可以大大减小的,但还有校准剩余称为“修正残余”(对一次校准是常值,对多次校准是随机变量)。本文也提出了修正残余的综合公式,并以液体火箭发动机测试系统的数字例来进行说明。这就提供了一种较完整的在给定置信度下综合测量设备误差的公式及方法。
In the past when making a comprehensive estimation of the precision and accuracy of measurement equipment, the mean of sample sub-samples and the variance of sub-samples were taken as the mean of maternal and maternal variance. Doing so often overestimates the accuracy and creates false accuracy. In recent years, some authors at home and abroad have introduced the concepts of confidence, uncertainty and limit error into their articles. However, the uncertainty and limit error are related to the degree of freedom, and the degrees of freedom of different error sources are not necessarily the same. Therefore, “square sum of square summation of the ultimate limit of error” method is only applicable to the freedom of the error sources are the same situation. In this paper, the formula of the limit error and uncertainty of different degrees of freedom is presented. The system error can be greatly reduced if the measuring device is calibrated, but there are also calibration residuals called “correction residuals” (constant values for one calibration and random variables for multiple calibrations). This paper also presents a modified residual integral formula, and to liquid rocket engine test system to illustrate the number of examples. This provides a more complete set of confidence in a comprehensive measurement of equipment error formula and method.