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4. Servo Adjustment
4 - 22
4-3-5 Improvement of protrusion at quadrant changeover
The response delay (caused by dead band from friction, torsion, expansion/contraction, backlash, etc.)
caused when the machine advance direction reverses is compensated with the lost motion compensation
(LMC compensation) function.
With this, the protrusions that occur at the quadrant changeover in the DBB measurement method, or
the streaks that occur when the quadrant changes during circular cutting can be improved.
The following three compensation types are available for lost motion compensation (LMC compensation).
[1] LMC compensation type 1
This is a backward compatible (for older models) compensation type. Either type 2 or type 3 should
be used on new models.
[2] LMC compensation type 2
Performs servo internal PI control response delay compensation for the frictional torque reversing
condition that occurs during servo reverse travel. Reverse response delay is compensated with
adding the torque command set by parameter when a speed and direction change occurs.
LMC compensation type 2 adjustments should be performed with reference to the following items.
(1) Unbalance torque and frictional torque
(2) LMC compensation type 2 setting and adjustment
(3) Lost motion compensation timing adjustment
(4) Adjustment at feed forward control
[3] LMC compensation type 3
In addition to frictional torque influence, this type compensates torsion and expansion/contraction
influences in the machine system in which compensation amount is changed by travel speed. A
mechanical system viscosity coefficient setting further enhances the compensation accuracy even
if the travel speed is changed. Adjustment requires a machine end roundness measurement.
LMC compensation type 3 adjustments should be performed with reference to the following items.
(1) Unbalance torque and frictional torque
(2) LMC compensation type 3 setting and adjustment
Circle cutting path before compensation
Compensation
Cutting
direction
DBB: Double Ball Bar
Circle cutting path after compensation