Glossary · Sensors and measurement
Repeatability
Also known as: Measurement repeatability, Repeat accuracy
German: Wiederholgenauigkeit
In metrology, repeatability is measurement precision under repeatability conditions: the same measurement procedure, operators, measuring system, operating conditions and location, with replicate measurements over a short period of time.
- Sensors
- Standards
In one sentence
Repeatability is how closely repeated measurements agree under the same conditions over a short time, a key figure for sensors and robots.
Example
A robot datasheet states a pose repeatability of ±0.02 mm, while its absolute positioning accuracy is considerably worse.
How it applies
- Engineering: Repeatability matters most where a process is taught or adjusted once and then repeated, such as switching points of sensors or taught robot positions. Absolute accuracy matters when positions are calculated from models or CAD data.
- Commissioning: Poor repeatability cannot be corrected by adjustment; it indicates mechanical play, noise or an unsuitable sensor.
- Quality: Measurement system analysis uses repeatability and reproducibility studies to decide whether a gauge is fit for a task.
- Documentation: Distinguish repeatability from accuracy in datasheets, specifications and marketing texts. The German Wiederholgenauigkeit is often translated as repeat accuracy, which suggests accuracy; repeatability is the clearer term.
Repeatability vs. accuracy
Repeatability describes scatter around the device's own mean. Accuracy describes closeness to the true value. A device can be highly repeatable and still inaccurate.