
3. α SERIES PARAMETER ADJUSTMENT B-65150E/04
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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
Subsec. 3.4.3 (6).
Fig. 3.4.3 (k) Velocity feed-forward adjustment
Swells in the arc areas can be reduced by increasing the velocity loop
gain (Fig. 3.4.3 (l)). However, figure errors that occur at the joints of
straight lines and arcs cannot be fully eliminated. Swells can be
additionally reduced by fine adjustment of the velocity feed-forward
coefficient or by using the arc radius based feedrate clamp function
described in Subsec. 3.4.3 (6).
The figure display is 5 mm wide.
The error
Machine vibration
caused by insufficient
velocity control
response is observed.
Figure errors in
this area cannot
be fully eliminated
by increasing the
velocity loop gain.
Swells can be
reduced by
increasing the
velocity loop gain.
Fig. 3.4.3 (l) Velocity feed-forward adjustment
Velocity loop gain: 300%
Advanced preview feed-forward coefficient: 99%
FAD time constant: 24 ms (linear type)
Velocity feed-forward: X120%, Y180%