Rockwell Automation 999 IMC S Class Compact Motion Controller (Cat. No. 4100-999-122) - Manual (Page 37)

Technical Overview 3-7
Publication 999-122 - January 1997
Indexing and Jogging
The indexer moves the axis using either a trapezoidal, parabolic, or
S-Curve (controlled jerk) velocity profile. Axis velocity, acceleration,
and deceleration are completely programmable. The trapezoidal profile
is the most common type of move and results in a smooth acceleration
to the desired speed and a smooth deceleration to the desired destination
position. Parabolic and S-curve profiles are provided for use where
minimum stress on the mechanics is more important than minimum
index time.
The jogger produces constant speed motion of the axis in either
direction. The velocity and the acceleration rate are programmable. The
indexer and jogger also provide the ability to change speeds and index
positions while the axis is moving. The jogger also allows changes in
the acceleration or deceleration ramp while jogging. Furthermore,
electronic gearing may be combined with index and jog motion to create
complex motion profiles and synchronizations.
Backlash Compensation
Another high level motion function is Backlash Compensation. This
technique–called Unidirectional Approach–overcomes mechanical
backlash by always approaching the destination position from the same
direction. When approaching the destination position from the opposite
direction, the axis moves past the destination position by a
programmable Backlash Offset, reverses, and then moves back to the
destination position. Since the axis always approaches the destination
position from the same direction, the mechanical backlash is always
taken up in the same direction ensuring accurate positioning.
Electronic Cam
The electronic cam feature provides the IMC-S/23x with the ability to
execute coordinated motion profiles. This is accomplished by
programming a table of position values which describe the desired
profile, and then executing the table as required. Electronic cams may
be defined in terms of axis position(s) versus time (time-lock cams) or
position of the slave axis versus position of the master axis
(position-lock cams).
Electronic Gearing
Electronic gearing allows any axis to be programmed to track another
axis at a specified ratio. By convention, the axis that is tracking is called
the slave, while the axis that is being tracked is called the master. Thus,
the master axis is equivalent to the input shaft, and the slave axis to the
output shaft in a mechanical transmission.