6.10 Axis correction
The position value delivered by the encoder system and the actual position value on
the axis may vary for a number of reasons. Such non-linear inaccuracies can be
compensated by axis error correction (using position- and direction-dependent
correction values). For this, a correction value table is filled with values for each of
the two directions. The respective correction value is produced from the current axis
position and the direction of movement by means of cubic, jerk-stabilized
interpolation. The position value is adapted on the basis of the corrected table. Both
tables contain 250 interpolation points.
The correction range is within the value range delimited by parameters
P 591 -
ENC_ACOR_PosStart
"Start position" and
P 592 - ENC_ACOR_PosEnd
"End
position correction". The start position is preset on the user side; the end position is
determined on the drive side.
Possible cause of deviations
Inaccuracy of the measuring system
Slack in mechanical elements such as the gearing, coupling, feed spindle
etc.
Thermal expansion of machine components.
MOOG
ID
No.:
CB40859-001
Date:
02/2018
MSD Servo Drive - Device Help
97
6 Encoder
Fig. 6.11: Mechanical system axis correction (① = slack in gearing)
P No.
Index Name / Setting
Unit Description
530
0
ENC_Encoder1Sel
Channel selection for the 1st Encoder
531
0
ENC_Encoder2Sel
Channel selection for the 2nd Encoder
590
0
ENC_ACOR_Sel
0 (= OFF)
No encoder selected
1 (= 1st Encoder)
1. encoder selected
2 (= 2nd Encoder)
2. encoder selected
591
0
ENC_ACOR_PosStart
Definition of correction range: The range is
defined by parameters
P 0591 ENC_ACOR_
PosStart
Start position and
P 0592 ENC_ACOR_PosEnd
end position.
The start position is user-specified; the end
position is determined on the device side from
the maximum value of correction table
interpolation points used and the interpolation
point pitch
592
0
ENC_ACOR_PosEnd
Table 6.34: Axis correction parameters
