Omron TJ1-MC04 - PROGRAMMING 1 Programming Manual page 246

Examples and tips
Example 3
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 Trajexia 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 encoder_counts
UNITS =
.
Pn203 1 motor_revolution
17
.
2 6.31 encoder_counts
320 mm
Therefore:
17 17
.
Pn202 2 6.31 2
UNITS = =
5
Pn203 320 2
One solution is:
UNITS = 2 = 512
Pn202 = 631
Pn203 = 125
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:
PROGRAMMING MANUAL
. .
6.31 motor_revolution 1 pulley_revolution
.
1 pulley_revolution 320mm
631 631 631 631
12 9
12
= 2 = 2 = 2
3
.
1000 8.125 2 125 125
9
M
17-bit absolute 1:6.31
encoder Gear
1 turn = 320mm move
=
fig. 21
Total length (perimeter) of belt: 4160
r
r = 320/(2*PI)
246