
B-65270EN/05 APPENDIX H.DETAILS OF HIGH-SPEED AND HIGH-PRECISION ADJUSTMENT
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In Fig. H (i), excessively large velocity feed-forward coefficients are
specified, so that the protrusions shown in Fig. H (g) have changed to
cuts, and the cuts have changed to protrusions. This means that
optimum velocity feed-forward coefficients exist and they are less
than the values of Fig. H (i). Fig. H (j) shows the result of adjustment
to the optimum values. Fig. H (k) enlarges the errors only for display.
Fig. H (i)
elocity feed-forward adjustment
Velocity loop gain: 100%
Advanced preview feed-forward coefficient: 99%
FAD time constant: 24 ms (linear type)
Velocity feed-forward: X200%, Y200%
Fig. H (j)
elocity feed-forward adjustment
Velocity loop gain: 100%
Advanced preview feed-forward coefficient: 99%
FAD time constant: 24 ms (linear type)
Velocity feed-forward: X120%, Y180%
When the enlarged range is viewed, it is seen that the machine is
vibrating in the arc areas. This vibration is caused by a low velocity
loop gain. To reduce this vibration, two methods are available. One
method increases the velocity loop gain. (This method cannot be used
when the velocity loop gain has already been increased to the
oscillation limit.) The other method decreases the feedrate in the arc
areas with the arc radius based feedrate clamp function as described in
Item H (4).
The figure display is 5 mm wide.
The error is 10
m in size.
Machine vibration
caused by insufficient
velocity control
response is observed.
Fig. H (k) Velocity feed-forward adjustment