15
Control System Configuration
Section 1-4
Internal Operation of the
MC Unit
Inferred closed loop systems occupy the mainstream in modern servo sys-
tems applied to positioning devices for industrial applications. The following
graph shows the basic principle of the Servo System as used in the MC Unit.
1,2,3...
1.
The MC Unit performs actual position control. The main input of the con-
troller is the following error, which is the calculated difference between the
demand position and the actual measured position.
2.
The Position Controller calculates the required speed reference output de-
termined by the following error and possibly the demanded position and
the measured position. The speed reference is provided to the Servo Driv-
er.
3.
The Servo Driver controls the rotational speed of the Servomotor corre-
sponding to the speed reference. The rotational speed is proportional to
the speed reference.
4.
The rotary encoder will generate the feedback pulses for both the speed
feedback within the Servo Driver speed loop and the position feedback
within the MC Unit position loop.
Motion Control Algorithm
The servo system controls the motor by continuously adjusting the speed ref-
erence to the Servo Driver. The speed reference is calculated by the MC
Unit’s Motion Control algorithm, which is explained in this section.
The Motion Control algorithm uses the demand position, the measured posi-
tion and the following error to determine the speed reference. The following
error is the difference between the demanded and measured position. The
demand position, measured position and following error are represented by
axis parameters MPOS, DPOS and FE. Five gain values have been imple-
mented for the user to be able to configure the correct control operation for
each application.
Position
Control
Speed
Control
Motor
Encoder
Measured
speed
Measured
position
Demand
position
Speed
reference
1
2
3
4
MC Unit
Servo System
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