Mitsubishi Electric MELSERVO-J3 Series Manual page 349

Part 5: Common Reference Material
(b) Adjustment procedure of the lost motion compensation function
1) Measuring the load current
Measure the load currents during the forward direction feed and reverse direction feed with MR
Configurator2.
2) Setting the lost motion compensation
Calculate the friction torque from the measurement result of (9) (b) 1) of this section and set a
value twice the friction torque in [Pr. PX36] and [Pr. PX37] as lost motion compensation.
Friction torque [%] =
3) Checking protrusions
Drive the servo motor and check that the protrusions are corrected.
4) Adjusting the lost motion compensation
When protrusions still occur, the compensation is insufficient. Increase the lost motion
compensation by approximately 0.5% until the protrusions are eliminated. When notches occur,
the compensation is excessive. Decrease the lost motion compensation by approximately 0.5%
until the notches are eliminated. Different values can be set as the compensation for each of
when the forward rotation (CCW) switches to the reverse rotation (CW) and when the reverse
rotation (CW) switches to the forward rotation (CCW).
5) Adjusting the lost motion compensation timing
When the machine has low rigidity, the speed loop gain is set lower than the standard setting
value, or the servo motor is rotating at high speed, quadrant projections may occur behind the
quadrant change points. In this case, you can suppress the quadrant projections by delaying the
lost motion compensation timing with [Pr. PX41 Lost motion compensation timing]. Increase the
setting value of [Pr. PX41] from 0 ms (Initial value) by approximately 0.5 ms to adjust the
compensation timing.
|(load current during feed in the forward rotation direction [%]) -
(load current during feed in the reverse rotation direction [%])|
Travel
direction
The locus before compensation
Travel
direction
Before timing delay compensation
5 - 164
2
Compensation
The locus after compensation
Compensation
After timing delay compensation