Accuracy; Conveyor Resolution Error - YASKAWA MOTOMAN DX200 Instructions Manual

165637-1CD
Conveyor Synchronized
Function
6.2
6.3
6 Playback

6.2 Accuracy

Accuracy
The conveyor synchronized operation function reproduces the path taught
with the conveyor in stop status.
Therefore, the accuracy of conveyor synchronized operation function is
determined by the amount of difference between the taught path and the
synchronized path. Since the object is moving, it is impossible to
appreciate the accuracy in the same way as the repetitive positioning
accuracy for the still-object.
The amount of difference between the taught path and the synchronized
path is resulted from the following factors in interaction. Even if the
following factors are adjusted not to cause the difference, the difference
shows about ten times the difference from repetitive positioning for still-
object.
• Linearity of the conveyor in the synchronization section.
• Conveyor movements that are not indicated in motion pulse data
from a conveyor encoder (such as swings with a hanger conveyor).
• Differences between the manipulator actual dimensions and the
dimensions registered in DX200.
• Conversion resolution error that occurs when converting the
conveyor motion pulse (number of pulses) from the conveyor
encoder to the conveyor moving amount (mm). The details of
conversion resolution error will be explained in section 6.3

"Conveyor Resolution Error".

• Manipulator mechanical accuracy such as arm bending.
• Follow-up delay for the conveyor speed fluctuation.
• Manipulator system lag time.
• Difference between the conveyor moving direction and the traveling
axis moving direction when the synchronization is performed by the
traveling axis.
Conveyor Resolution Error
The synchronization error resulted from the conveyor resolution setting
error increases as the conveyor position value increases. The farther the
conveyor moves, the bigger the synchronization error becomes. The
minimum value for conveyor positional resolution setting is 0.01 μm.
Therefore, a maximum error of 0.005 μm per pulse may occur.
For example, when the conveyor resolution is 10 μm and the
synchronization distance is 2 m, 200000 pulses are output while the
conveyor moves for 2 m. Since the maximum error per pulse is 0.005 μm,
the synchronization error would be: 200000 pulses ∗ 0.005 μm = 1 mm.
6-2
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