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12 CONTROL AUXILIARY FUNCTIONS
(1) Error compensation method
When position control is carried out by the "movement amount per pulse" set in
the D75P2 parameters, an error sometimes occurs between the command
movement amount (L) and the actual movement amount (L').
That error is compensated in the D75P2 by adjusting the values in "
Pr.2 No.
of pulses per rotation (Ap)", "
Pr.3 Movement amount per rotation (Al)", and
"
Pr.4 Unit magnification (Am)". (When " Pr.1 Unit setting" is "0: mm")
(a) Definition
The "error compensation amount" used to carry out the error compensation
is defined as follows.
Error compensation amount =
Actual movement amount (L')
Designated movement amount (L)
The D75P2 "movement amount per pulse" is calculated with the following
equation.
Movement amount per pulse is "A",
Pr.2 No. of pulses per rotation is
(Ap),
Pr.3 Movement amount per rotation is (Al), and Pr.4 Unit
magnification is (Am).
A =
Al
Am
Ap
(b) Procedure
1) Set the "command movement amount (L)", and carry out positioning.
(Set the "movement amount per pulse (A)" according to section "5.2
List of parameters".)
2) After positioning, measure the "actual movement amount (L')".
3) Calculate the "error compensation amount".
Error compensation amount =
L'
L
4) Calculate the post-compensation "
Pr.2 No. of pulses per rotation
(Ap')", "
Pr.3 Movement amount per rotation (Al')", and " Pr.4
Unit magnification (Am')" from the "post-compensation movement
amount per pulse (A')".
A = A
Error compensation amount
=
Al
Am
L'
Ap L
=
Al'
Am'
Ap'
(Adjust with Am' so that Al' and Ap' do not exceed the setting range.)