Wednesday, May 2, 2012

The meaning of “accurate”

As engineers, we deal in precision, so when someone asks how accurate a vision system will be it’s important to give a precise answer. But that depends on understanding accuracy, and in my experience, many people use the word without being able to explain what it they mean by it.

Now it’s not my practice to get in to long explanations and tutorials when someone has already done it for me, so please allow me to direct you to an article published in Control Design all the way back in 1999.

Accuracy: Know What You’re Getting” provides a very detailed explanation of measurement precision. There’s also an excellent glossary that defines terms such as repeatability and reproducibility, and if you don’t know the difference, click the link and educate yourself!

I will concede that plowing through the four pages is hard work, but stick at it because this is what underpins every machine vision application you will ever work on. Even if you system isn’t gauging you still need to demonstrate accuracy. Or do I mean repeatability? Or bias?

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