Rockwell Automation 1398-PDM-xxx IQ Master Version 3.2.4 for IA-2000 and IQ-5000 Positioning Drive Modules, IQ-55 - Manual (Page 146)

124 • S-Curve Acceleration
Publication 1398-PM601A-EN-P — October 2000
TUTORIAL
can be programmed using DV moves.
From the following table, write a program to execute the move profile shown, and run it.
The program for this profile should look something like this:
TITLE "stkmoves"
D = 3,V = 56
D = 3,V = 12
D = 4,V = 16
D = 2,V = 57
D = 2.5,V = 61
D = 3,V = 11
D = 5,V = 20
D = 8,V = 0
END
S-Curve Acceleration
Very often it is important for a move profile to be as smooth as possible. This could be to minimize the
wear on a machine, or it could be that a smooth profile is critical to the successful completion of an
operation. To perform smooth motion profiles, the ULTRA Plus or IQ supports S-Curve acceleration.
The following diagram illustrates the difference between straight and S-Curve acceleration.
With normal, straight line acceleration, the axis is accelerated to the target velocity in a linear fashion.
S-Curve acceleration accelerates the axis slowly at first, twice as fast as the straight line acceleration in
the middle, and then slowly stops accelerating. With straight line acceleration, the acceleration changes
abruptly and then at the end of the acceleration period, changes abruptly again to no acceleration (see
the Acceleration Profile). With S-Curve acceleration the acceleration gradually builds to the peak value
then gradually decreases to no acceleration. The disadvantage with S-Curve acceleration is that for the
same acceleration distance the peak acceleration is twice that of straight line acceleration—which often
requires twice the peak torque. Notice that the axis arrives at the end of the stick position at the same
Stick Number Distance moved during stick Velocity at end of stick
1 3 56
2 3 12
3 4 16
4 2 57
5 2.5 61
6 3 11
7 5 20
8 8 0