ABB OmniCore, Operating Manual

Page: 145 / 266

6 Tap Next . The Calculation Result dialog box will now be displayed, asking
you to cancel or to confirm the result before it is written to the controller.
For further information see Is the calculated result good enough? on page 145
How to define elongator points
This procedure describes how to define the orientation of the tool frame by
specifying the direction of the z and/or x axis. You need to do this only if you the
tool orientation should differ from that of the robot base. The tool coordinate system
by default resembles the coordinate system of tool0, as illustrated in
Measuring
the tool center point on page 146 .
1 Without changing the orientation of the tool, jog the robot so that the reference
world point becomes a point on the desired positive axis of the rotated tool
coordinate system.
2 Tap Modify to define the point.
3 Repeat step 1 and 2 for the second axis if it should be defined.
Is the calculated result good enough?
The Calculation Result dialog box displays the calculated result of the tool frame
definition. You have to confirm that you accept the result before it can take effect
in the controller. The alternative is to redo the frame definition in order to achieve
a better result. The result
Mean Error is the average distance of the approach
points from the calculated TCP (tool center point). Max Error is the maximum error
among all approach points.
It is hard to tell exactly what result is acceptable. It depends on the tool, robot type
etc. you are using. Usually a mean error of a few tenths of a millimeter is a good
result. If the positioning has been undertaken with reasonable accuracy the result
will be okay.
As the robot is used as a measuring machine, the result is also dependent on
where in the robot’s working area the positioning has been done. Variation of the
actual TCP up to a couple of millimeters (for large robots) can be found between
definitions in different parts of the working area.The repeatability of any following
TCP calibrations will thus increase if these are done close to the preceding ones.
Note that the result is the optimal TCP for the robot in that working area, taking
into account any discrepancies of the robot in the configuration at hand.
Tip
A common way to check that the tool frame has been correctly defined is to
perform a reorientation test when the definition is ready. Select the reorient
motion mode and the tool coordinate system and jog the robot. Verify that the
tool tip stays very close to the selected reference point as the robot moves.
Operating manual - OmniCore 145
3HAC065036-001 Revision: J
© Copyright 2019-2021 ABB. All rights reserved.
6 Programming and testing
6.6.5 Defining the tool frame
Continued