Mitsubishi Electronics QD75P, QD75D user manual Error compensation method, Definition, Procedure

12CONTROL SUB FUNCTIONS

[1]Error compensation method

MELSEC-Q

When position control is carried out by the "movement amount per pulse" set in the QD75 parameters, an error sometimes occurs between the command movement amount (L) and the actual movement amount (L').

That error is compensated in the QD75 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")

(1) 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 QD75 "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 "

magnification" is (Am).

Pr.4

Unit

Al

A = ⋅ Am

Ap

(2)Procedure

(a)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".)

(b)After positioning, measure the "actual movement amount (L')".

(c)Calculate the "error compensation amount".

L'

Error compensation amount =

L

(d) 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.)

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