Omron 8U0108-E1-01, User Manual

Page: 94 / 333

XtraDrive User Manual Chapter 5 : Parameter Settings and Functions
5-26
2. Determine the reference unit used.
A reference unit is the minimum position data unit used to move a
load (minimum unit of reference from the host controller).
Reference unit: 0.001 mm
Determine the reference unit according to
equipment specifications and positioning accuracy.
To move a table in 0.001 mm units
Examples (in mm):
•
Reference unit can be 0.1in or 0.01in or 0.01mm or 0.001mm,
etc. A reference unit of one pulse moves the load by one
reference unit.
•
When the reference unit is 1 µ m
If a reference of 50000 units is input, the load moves 50mm
(1.97in) (50000
⋅
0.00
1
mm = 50mm).
3. Determine the travel distance per load shaft revolution in reference
units.
Travel distance per load shaft revolution =
Unit Reference
revolution shaft load per distance Travel
•
When the ball screw pitch is 0.20in (5mm) and the reference unit
is 0.00004in (0.001mm),
00004 . 0
20 . 0
= 5000 (reference units)
Ball Screw Disc Table Belt and Pulley
π
π
4. Electronic gear ratio is given as:






A
B
If the gear ratio of the motor and the load shaft is given as:
n
m
where
m is the rotation of the motor and n is the rotation of the load shaft,
Electronic gear ratio 





A
B
=
unit) (reference revolution shaft load per distance Travel
4 x pulses encoder of Number
x
n
m
Note: Make sure the electronic gear ratio satisfies the following condition:
0.01 ≤ Electronic gear ratio






A
B
≤ 100
The servo amplifier will not work properly if the electronic gear ratio exceeds this range. In that case,
modify either the load configuration or the reference unit.