Yaskawa FSP Amplifier - Manual (Page 93)

FSP Amplifier User’s 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 0.1 in or 0.01 in or 0.01 mm or 0.001 mm,
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 50 mm (1.97
in) (50000
⋅ 0.001 mm = 50 mm).
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 0.20 in (5 mm) and the reference unit
is 0.00004 in (0.001 mm),
00004 . 0
20 . 0
= 5000 (reference units)
Ball Screw Disc Table Belt and Pulley
1 revolution = 1 revolution =
1 revolution =
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.
reference unit reference unit
reference unit 1 revolution =
1 revolution =
1 revolution =