Omron CS1W-MC221 -, Operation Manual

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12
Control System Configuration and Principles Section 1-4
1-4 Control System Configuration and Principles
1-4-1 Servo System
The servo system used by and the internal operations of the MC Unit are
briefly described below.
Semi-closed Loop System The servo system of the MC Unit uses a semi-closed loop system. This sys-
tem is designed to detect actual machine movements by rotation of the motor
in relation to a target value. It computes the error between the target value
and actual movement, and zeroes the error through feedback.
Semi-closed loop systems occupy the mainstream in modern servo systems
applied to positioning devices for industrial applications.
Internal Operations of the
MC Unit Commands to the MC Unit, speed control voltage to the servo driver, and the
feedback signals from the encoder are described in the next few pages.
1,2,3... 1. The error counter receives a target position in units of encoder pulses. This
is called a pulse string.
2. The error counter is directly connected to the D/A converter where the
pulses received by the error counter are converted to analog voltages.
These analog voltages are sent to the servo driver as the speed control
voltages.
Table
Ball screw
Decelerator
Actual
movement
Target value
Position controller
Encoder
Servomotor
Desired position
Pulse string
Error
counter D/A
converter Servo driver Servomotor
Speed
feedback
Encoder
Position feedback
Feedback pulses
Speed
control
voltage