Mitsubishi Electric RD77MS2 User Manual page 232

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 Simple Motion module, this error is
compensated by adjusting the electronic gear.
The "Error compensation amount", which is used for error compensation, is defined as follows:
Error compensation amount =
The electronic gear including an error compensation amount is shown below.
AP
×
AL × AM L'
Simple Motion module
Command
Control
unit
value
Simple Motion module
Command Control
unit
value
■Calculation example
(Conditions)
Number of pulses per rotation (AP) : 4194304 [pulse]
Movement amount per rotation (AL) : 5000.0 [μm]
Unit magnification (AM)
(Positioning results)
Command movement amount (L) : 100 [mm]
Actual movement amount (L')
(Compensation value)
AP
AL × AM
Number of pulses per rotation (AP') : 4194304
Movement amount per rotation (AL') : 5050.0
Unit magnification (AM')
Set the post-compensation "[Pr.2] Number 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 Simple Motion module. The set details are validated
at the rising edge (OFF  ON) of the PLC READY signal [Y0].
8 CONTROL SUB FUNCTIONS
230
8.3 Functions for Compensating the Control
Command movement amount (L)
Actual movement amount (L')
L AP'
=
AL' × AM'
AP
AL × AM
Electronic gear taking an error into consideration
AP'
AL' × AM'
L 4194304
×
=
L' 5000.0 × 1
L
pulse
L'
1 if there is no error (in regular case)
pulse
: 1
: 101 [mm]
100
× =
101 5050(AL') × 1(AM')
[Pr.2]
[Pr.3]
: 1 [Pr.4]
(2)
Servo amplifier
Servo amplifier
4194304(AP')