Measuring system
A measuring system is the entirety of the measuring device or measuring equipment , people and the environment .
Due to many possible causes, it is generally not possible to measure correctly, i.e. the measuring system can not record the measured variable without errors. The deviation of a measured value from the true value of the measured variable was previously called measurement error. Today, according to DIN 1319-1: 1995, the term measurement deviation is used.
The measurement uncertainty is an estimated value that indicates how large the distance between the measured and the true value of the measured variable can be. As cross-sensitivity which is called sensitivity of a measurement system for secondary, d. H. Measured variables that are not primarily to be measured.
The accuracy of the measuring system such as the result and the quality of a measurement are determined by various factors such as: B.
- Type and age of the measuring equipment or measuring device as well as its frequency of use
- existing ambient temperature , air flow or wind speed
- Type of interactions between people and measuring equipment or measuring device
- parallax
and many other factors are influenced to a greater or lesser extent, which is why various methods for controlling and monitoring measuring systems have become established in metrology ( measurement technology ), quality management ( quality assurance ) and in Six Sigma .
These include u. a. the repeated verification , calibration and adjustment of measuring devices within fixed specified tolerances or the analysis of the process capability of the entire measuring process including the measuring system, called measuring system analysis .
Possible causes for measurement errors in measurement systems are, on the one hand, systematic errors that can usually be influenced , such as
on the other hand, random errors that cannot be influenced, such as B. humidity , air turbulence or thermal noise .
Offset denotes constant systematic measurement errors in a measurement system, trend or drift denote increasing or decreasing measurement errors in a measurement system.