Yaskawa Sigma II Series Servo System - Manual (Page 115)

Sigma II User’s Manual Chapter 5: Parameter Settings and Functions
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number of encoder signal pulses (A and B phase) output from the servo amplifier.
3. 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).
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 1µm
If a reference of 50000 units is input, the load moves 50mm (1.97in)
(50000 × 0.001mm = 50mm).
4. Determine the load travel distance per load shaft revolution in reference units.
• When the ball screw pitch is 0.20in (5mm) and the reference unit is
0.00004in (0.001mm),
Ball Screw Disc Table Belt and Pulley
Reference unit: 0.001mm
Determine the reference unit according to
equipment specifications and positioning accuracy.
To move a table in 0.001mm units
Travel distance per load shaft revolution = Travel distance per load shaft revolution
Reference Unit
0.20
0.00004
--------------------- 5000 =
(reference units)
Load shaft
P
1 revolution =
P
reference unit
P: Pitch
L d h ft Load shaft
1 revolution =
360°
reference unit 1 revolution =
πD
reference unit
D: Pulley
πΔ
Load shaft