10 March 2014: Stephan Conrad

Even the ancient Egyptians already had a “royal cubit master” based on the length of the Pharaoh’s forearm. It was carved out of a block of granite and served as reference. They say that royal architects and foremen had to compare their cubit sticks to the royal cubit at each full moon and transfer the unit of length to the workers’ instruments. It was death for them to fail to do so.

Instead of spending our time on severe punishments within the context of the first known monitoring of test equipment, we rather visit beautiful Paris, the “city of love”. You can find a “marble meter bar” on several street corners. Merchants compared the length of their measuring sticks to the “marble meter” and adapted it. In 1795, Paris was the city where the first provisional meter bar (mètre des archives) was constructed of brass. The platinum meter bar was also produced there in 1799.

Finally, in 1889, a third mètre des archives was constructed out of platinumiridium. It was the international prototype meter between 1889 and 1960. After 1960, a definition of the meter in terms of the wavelength in vacuum of the radiation relating to a transition between specific energy levels of the krypton 86 atom was adopted. This definition replaced the international prototype meter; however, in 1983, the meter became the length of the path travelled by light in vacuum during a specified time interval. All these changes since 1799 only had one goal – to increase the precision of this measure of length.

Due to the well-known problems caused in the calculation of measurement uncertainty, the international Bureau of Weights and Measures decided in 1977 to develop an international agreement on the expression of measurement uncertainty. They provided the first proposal in 1980 which was confirmed in 1981. However, it took another five years until the ISO Advisory Group on Metrology was entrusted with preparing a detailed guideline. This guideline was published in 1995 and is still known as the “Guide to the expression of uncertainty in measurement” (GUM).

If you compare the cars of 1977 to the cars of 1995, you will quickly realize that, within the scope of globalization, the automotive industry had no interest at all to wait for this standard for such a long time. In 1989, Ford published a twelvepage document for the evaluation of measurement systems. For the first time, this document described two specific test procedures – both, type-1 and type-2 study, are still known today.
Other automotive companies followed suit an already in 1990, the AIAG published the first edition of the AIAG MSA manual that aimed at standardizing these methods. Even Bosch published the first booklet 10 for the evaluation of measurement systems in 1990...