Mitsubishi Electric MELSERVO-J4 Series Instruction Manual page 279

■Lost motion filter setting ([Pr. PE46])
Changing the value of this parameter is usually unnecessary. When a value other than 0.0 ms is set in this parameter, the
high-pass filter output value of the set time constant is applied to the compensation and lost motion compensation continues.
Adjustment procedure of the lost motion compensation function
The following shows the adjustment procedure of the lost motion compensation function.
■Measuring the load current
Measure the load currents during the forward direction feed and reverse direction feed with MR Configurator2.
■Setting the lost motion compensation
Calculate the friction torque from the measurement result of the section below and set a value twice the friction torque in [Pr.
PE44] and [Pr. PE45] as lost motion compensation.
Page 277 Measuring the load current
|(load current during feed in the forward rotation direction [%]) -
(load current during feed in the reverse rotation direction [%])|
Friction torque [%] =
■Checking protrusions
Drive the servo motor and check that the protrusions are corrected.
■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).
Compensation
Travel
direction
The locus before compensation
■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. PE49 Lost motion compensation timing].
Increase the setting value of [Pr. PE49] from 0 ms (Initial value) by approximately 0.5 ms to adjust the compensation timing.
Travel
direction
Before timing delay compensation
2
The locus after compensation
Compensation
After timing delay compensation
7 SPECIAL ADJUSTMENT FUNCTIONS
7.6 Lost motion compensation function
7
277