
4. SERVO FUNCTION DETAILS B-65150E/04
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Example)
When feed operation is performed using F1800 with a position
gain of 30 (1/s) and a detection unit of 0.001 mm, the positional
deviation is normally expressed as follows:
Feedrate (mm/min)
=
60 × Position gain (1/s) × Detection unit (mm)
1800
= × 1000 (pulses)
60 × 30 × 0.001
When the FAD function is used with the time constant set to 64
ms, the deviation increases as follows:
1800 64
= × + 1 = 990 (pulses)
60 × 1000 × 0.001 2
When FAD is used, the entire deviation is then obtained as
follows:
Deviation when FAD is used (pulses) = 1000 + 990
= 1990 (pulses)
The combined use of the FAD function and the feed-forward function
does not increase the positional deviation so much as expected, because
the feed-forward function decreases a delay against the command.
When the FAD function is used alone, however, a higher error
overestimation level must be set, considering the increase in the
deviation.
Normal
deviation
(pulses)
Deviation
increase
(pulses)