MITSUBISHI ELECTRIC Mitsubishi Programmable Logic Controller QD75D - Manual (Page 31)

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MELSEC-Q
1 PRODUCT OUTLINE
(a) In the system shown in Fig. 1.4, the movement amount per pulse,
command pulse frequency, and the deviation counter droop pulser amount
are determined as follows:
1) Movement amount per pulse
The movement amount per pulse is determined by the worm gear lead,
deceleration ratio, and the pulse encoder resolution.
The movement amount, therefore, is given as follows: (Number of
pulses output) × (Movement amount per pulse).
L
A =
R
×
n
[mm/pulse]
2) Command pulse frequency
The command pulse frequency is determined by the speed of the
moving part and movement amount per pulse:
V
Vs =
A
[pulse/s]
3) Deviation counter droop pulser amount.
The deviation counter droop pulser amount is determined by the
command pulse frequency and position loop gain.
Vs
ε
=
K
[pulse]
(b) The QD75 allows the user to select from the following four units as the unit
used by positioning commands to any of the axes (1 to 4, if the module
supports four axes): mm, inch, degree, and pulse.
The unit selected for one axis may differ from the unit selected for another
axis.
When such data as the movement amount per pulse,
acceleration/deceleration time, positioning speed, and positioning address
are correctly set in consideration of the chosen unit, the QD75 can calculate
the number of pulses required for a movement amount to the target
positioning address and execute the positioning by outputting a pulse train
that includes the calculated number of pulses.