Examples and tips
PROGRAMMING MANUAL
241
Revi
si
on 3.0
Example 1
fig. 19
The mechanical system consists of a simple rotary table. A servo
motor with 13-bit incremental encoder is used. The gear ratio of the
gearbox is 1:10.
The desired user units are degree of angle. This system can be
described with the following equations:
The combination of these equations results in:
And therefore:
From this equation, we can derive the values for Pn202, Pn203 and
UNITS
, given the following restrictions and recommendations:
1. Pn202 and Pn203 are integers.
2. UNITS must not have an infinite number of decimal digits. This
can create rounding errors that result in small position errors
that add up to large accumulative position errors.
3. For reasons of stability, it is necessary to avoid situations where
Pn202/Pn203 is less than 0.01 or greater than 100.
We can now rewrite the last equation to:
1:10 Gear
13-bit
incremental
encoder
Full turn = 360
M
1
motor_revolution =
2
13
encoder_counts
10
motor_revolution =
1
machine_cycle
1
machine_cycle =
360
o
.
.
.
.
.
Pn202
Pn203
UNITS =
=
.
2
13
13
encoder_counts
1 motor_revolution 1 machine_revolution
10 motor_revolution
360
1 machine_revolution
o
360
2 10
degree
encoder_counts
.
.
.
.
.
.
Pn202
Pn203
UNITS =
.
2
13
10
360
.
I52E-EN-03.book Seite 241 Freitag, 29. Juni 2007 11:55 11