Accuracy and Repeatability Explained

What Accuracy and Repeatability Mean in Automation and Robotic Applications

Device Accuracy

Position accuracy is the ability of the device to go to a specific programmed position with a minimum of error. This can be a new position with each command.

Device Repeatability

Repeatability is the devices ability to go back to the same programmed position each time.
In rotating applications, accuracy and repeatability are provided as an angular measurement, generally in arc-minutes ( 1/60 of 1 degree) or arc-seconds (1/3600 of 1 degree).

Accuracy and Repeatability in Baseball – Batter Up!

Accuracy and Repeatability – Example

Consider the strike zone in baseball

Not Accurate, Not Repeatable

Not Accurate, Very Repeatable
 

How does a Gearbox Contribute to Accuracy and Repeatability?

Gearbox Accuracy

The performance of the gearbox can help to improve system accuracy. Backlash is the largest contributor from the gearbox. The lower the backlash, the higher the accuracy. In addition, runout of the gearbox output shaft can also contribute to system accuracy.

Gearbox Repeatability

Other performance characteristics such as torsional stiffness and hysteresis will have a greater affect on the repeatability than they do on accuracy. Accuracy and Repeatability work hand in hand . Ultimately, the system works the best when both are optimized

Onvio’s Dojen Zero Backlash Reducer is ideal for applications that require high accuracy and repeatability.

• True Zero Backlash
• High Shock Loads
• High torsional stiffness
• Linear Stiffness
• Accuracy within 1 arc-minute
• Repeatability within 20 arc-seconds
• Low Inertia
• High Efficiency – 85%