Omron SYSMAC CJ Operation Manual page 301

How-to's
5-1-3-5 Example 3
M
17-bit absolute 1:6.31
encoder Gear
1 turn = 320mm move
The mechanical system uses a servo motor with an 17-bit absolute encoder.
The mechanical gear ratio of the gearbox is 1:6.31. One rotation of the pulley
moves the moving part on the belt 320 mm. The total length of the belt, and
therefore the total moving range of the motion part, is 4160 mm.
The mechanical measurement units must be mm. This means that all axis
parameters and commands given to the CJ1W-MCH72 are expressed in mm.
Using the same procedure as in example 1, the equation expressing the
relationship between user units and encoder counts is:
17
.
Pn202
2
UNITS =
.
Pn203 1 motor_revolution
17
.
2 6.31 encoder_counts
320 mm
Therefore:
Pn202
UNITS =
Pn203
One solution is:
Note that we have not used the pulley radius in the calculation. This is to avoid
the use of π, which cannot be expressed as a fractional number). In toothed
pulleys, the number of teeth and mm per tooth is commonly used.
The calculation of the multiturn limit setting is:
. .
m motor_revolution = n machine_cycle
. .
m motor_revolution = n machine_cycle
.
6 31 motor_revolution
.
= n 13
1 pulley_revolution
.
m = n 82.03
The smallest integer m for which this equation is valid is 8203. This results in
Pn205 = 8202.
Total length (perimeter) of belt: 4160
r
r = 320/(2*PI)
.
encoder_counts 6.31 motor_revolution
.
1 pulley_revolution
17 17
.
2 6.31 2 631
12
= = 2
5
320 2 1000
9
UNITS = 2 = 512
Pn202 = 631
Pn203 = 125
.
4160 pulley_revolution
.
320 machine_cycle
. .
= n 82.03 pulley_revolution
Section 5-1
.
1 pulley_revolution
320mm
631 631 631
12 9
= 2 = 2
3
.
8.125 2 125 125
. .
= n 13 pulley_revolution
=
289