Mitsubishi A1SD75P1-S3 User Manual page 32

1 PRODUCT OUTLINE
The principle of "position control" and "speed control" operation is shown below.
When this total No. of pulses is issued from the AD75 to the servo amplifier, control to
move the designated distance can be executed.
The machine side movement amount when one pulse is issued to the servo amplifier is
called the "movement amount per pulse". This value is the min. value for the workpiece
to move, and is also the electrical positioning precision.
Positioning
module
Speed = Pulse frequency
Movement amount = No. of pulses
Feedback pulses =
Pulses generated by detector
Fig.1.1 Relationship between position control and speed control
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Position control
The total No. of pulses required to move the designated distance is obtained in the
following manner.
Total No. of pulses
required to move
Movement amount of machine (load)
designated distance
side when motor rotates once
* The No. of pulses required for the motor to rotate once is the "encoder resolution"
described in the motor catalog specification list.
Speed control
The above "total No. of pulses" is an element required for movement distance
control, but when carrying out positioning control or speed control, the speed must
also be controlled.
This "speed" is controlled by the "pulse frequency".
Servo
amplifier
Feedback pulse
POINT
The AD75 controls the position with the "total No. of pulses", and the speed with
the "pulse frequency".
Designated distance
Pulse frequency
[pps]
A
Servomotor
Detector
(Pulse
encoder)
ta
0.4
Movement amount t = 2
1 - 7
MELSEC-A
No. of pulses required
for motor to rotate once
This area is the total
No. of commanded
pulses.
(s)
td
1.2 0.4