Lost Motion Compensation Function - Mitsubishi Electric MR-J4-10B(-RJ) Instruction Manual

7. SPECIAL ADJUSTMENT FUNCTIONS

7.6 Lost motion compensation function

The lost motion compensation function corrects response delays (caused by a non-sensitive band due to
friction, twist, expansion, and backlash) caused when the machine travel direction is reversed. This function
contributes to improvement for protrusions that occur at a quadrant change and streaks that occur at a
quadrant change during circular cutting.
This function is effective when a high follow-up performance is required such as drawing an arc with an X-Y
table.
(1) Parameter setting
Setting [Pr. PE44] to [Pr. PE50] enables the lost motion compensation function.
(a) Lost motion compensation function selection ([Pr. PE48])
Select the lost motion compensation function.
(b) Lost motion compensation ([Pr. PE44]/[Pr. PE45])
Set the same value for the lost motion compensation for each of when the forward rotation switches
to the reverse rotation and when the reverse rotation switches to the forward rotation. When the
heights of protrusions differ depending on the travel direction, set the different compensation for
each travel direction. Set a value twice the usual friction torque and adjust the value while checking
protrusions.
(c) Torque offset ([Pr. PE47])
For a vertical axis, unbalanced torque occurs due to the gravity. Although setting the torque offset is
usually unnecessary, setting unbalanced torque of a machine as a torque offset cancels the
unbalanced torque. The torque offset does not need to be set for a machine not generating
unbalanced torque. The torque offset cannot be used for linear servo motors and direct drive motors.
Set 0.00%.
POINT
The lost motion compensation function is enabled only in the position control
mode.
The locus before compensation
[Pr. PE48]
0 0
Compensation
Travel
direction
The locus after compensation
Lost motion compensation selection
0: Lost motion compensation disabled
1: Lost motion compensation enabled
Unit setting of lost motion compensation non-sensitive band
0: 1 pulse unit
1: 1 kpulse unit
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