Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 14)

Chapter
3
3Ć1
Positioning Concepts
This chapter presents positioning concepts and terminology. If you are
thoroughly familiar with the concepts of closed-loop servo positioning,
you can skip ahead to chapter 4.
Closed-loop positioning is a precise means of moving an object from one
position to another. Typically, an electric motor supplies the mechanical
power, and the needed motion is linear. Therefore, we must convert the
rotary motion of the motor’s shaft to linear motion.
Axis Motion
One common method of converting rotary motion to linear motion is with
a leadscrew (Figure 3.1)
Figure 3.1
Leadscrew Converting Rotory Motor Motion Into Linear Axis Motion
Axis Motion
Motor
Shaft
Rotation
11999
Slide
The leadscrew assembly is referred to as the axis. A leadscrew assembly
consists of a long threaded shaft (the leadscrew) and slide having an
internal thread that matches the leadscrew. When the motor rotates the
leadscrew clockwise, the slide moves forward. When the motor rotates
the leadscrew counterclockwise, the slide moves backward.
Chapter Objectives
ClosedĆLoop Positioning