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Chapter 10 Adjustment
10–18
(4) Adjusting for feed forward control
In LMC compensation, a model position considering the position loop gain is calculated based on
the position command sent from the CNC, and compensation is carried out when the feed
changes to that direction. When the CNC carries out feed forward (fwd) control, overshooting
equivalent to the operation fraction unit occurs in the position commands, and the timing of the
model position direction change may be mistaken. As a result, the LMC compensation timing may
deviate, or compensation may be carried out two or more times.
If feed forward control is carried out and the compensation does not operate correctly, adjust with
the non-sensitive band (SV040: LMCT) during feed forward control. In this non-sensitive band
control, overshooting of a set width or less is ignored. The model position direction change point
is correctly recognized, and the LMC compensation is correctly executed.
This parameter is meaningless when feed forward control is not being carried out.
<Adjustment method>
If the compensation timing deviates during feed forward control, increase the LMCT setting by
1µm at a time.
Note that 2µm are set even when the LMCT is set to 0.
No. Abbrev. Parameter name Unit Explanation Setting range
SV040 LMCT Non-sensitive band
during feed forward
control
µm
This setting is valid only during feed forward control.
2 µm is set when this is set to 0. Adjust by increasing the
value by 1 µm at a time.
0 ~ 100
(µm)
POINT
Setting of the non-sensitive band (SV040: LMCT) during feed forward control is
effective for improving overshooting compensation mis-operation during feed
forward control.