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MELSEC-Q
12 CONTROL SUB FUNCTIONS
[2] The method for compensating the error
When the position control is carried out using the "Electronic gear" set in a
parameter, this may produce an error between the command movement amount
(L) and the actual movement amount (L'). With QD75MH, this error is
compensated by adjusting the electronic gear. The "Error compensation
amount", which is used for error compensation, is defined as follows:
Command movement amount (L)
Error compensation amount =
Actual movement amount (L')
…(2)
The electronic gear including an error compensation amount is shown
below.
AP L AP'
AL
×
AM
×
L'
=
AL'
×
AM'
Command
value
Control
unit
AP
AL AM
L
L'
PLS
Servo
amplifier
QD75MH
AP'
AL' AM'
Control
unit
Command
value
PLS
Servo
amplifier
1 if there is no error (in regular case)
Electronic gear taking an error
into consideration
QD75MH
Calculation example
(Conditions)
Movement amount per pulse : 262144 [PLS]
No. of pulses per rotation
: 5000.0 [
µ
m]
Unit magnification : 1
(
Positionin
g
results
)
Command movement amount (L)
Actual movement amount (L')
: 100 [mm]
: 101 [mm]
(
Com
p
ensation
AP L 262144 100 262144 (AP')
AL
×
AM
×
L'
=
5000.0
×
1
×
101
=
5050
(AL')
×
1(AM')
Movement amount per pulse
: 262144 …
Pr.2
No. of pulses per rotation
: 5050.0 ….
Pr.3
Unit magnification
: 1 ………...
Pr.4
Set the post-compensation "
Pr.2
No. of pulses per rotation (AP')",
"
Pr.3
Movement amount per rotation (AL')", and "
Pr.4
Unit
magnification (AM')" in the parameters, and write them to the QD75MH.
The set details are validated at the rising edge (OFF
ON) of the PLC
READY signal (Y0).