Measuring Positions And Calibration Statistics - Universal Robots CB3 Manual

2.7 Measuring Positions and Calibration Statistics

After step no.: 15, the robot will begin measure and identify the calibration. First a number of initial measure-
ments are collected. A preliminary calibration is calculated from those. Second, the final set of measurements
will be done and the final calibration will be calculated, see Figure 2.24 and 2.25.
Figure 2.24: Collecting measurements
Afterwards, A statistics is given which describes whether the found calibration is usable (shown in green, see
Figure 2.26) or problematic (shown with red, see Figure 2.27).
If the result was successful as expected and the Auto step box is checked, it will automatically continue to step
no: 16.
Otherwise, The calibration results will be shown in red and the calibration procedure will not be able to continue,
see Figure 2.27. Please check how the robot is mounted with the calibration horse and the calibration tools and
try again by redoing all the steps from no: 1.
Figure 2.26: Successful calibration
The section Calibration Results contains the statistics for the accuracy of the found calibration. The Control
Results are statistics for a number of control measurements done throughout the calibration process which only
are used to validate the calibration.
The statistics are given in two units a) millimeters (mm) and milliradians (mrad) which refers to the RMS
deviation in Cartesian space. The statistics contains the fields:
Mean deviation: The average deviation in millimeters and in milliradians between the positions measured
by the first and second robot
Standard deviation: The standard deviation calculated on basis of the above
Max deviation: The maximal measured deviation
2. Dual Robot Calibration
Figure 2.25: Calculating the calibration
Figure 2.27: Problematic calibration
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