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

Page 150

5-70

Understanding IMC-S/23x Setups

Publication 999-122 - January 1997

Setting the Proportional Gain

With the velocity gain tuned or set as outlined above, increase the
proportional gain from 0.01 to provide position control. In general, the
optimal setting for proportional gain is the largest value that does not
cause excessive overshoot or oscillation when stopping.

A well-tuned system will move and stop quickly or "smartly" and
exhibit little or no "ringing" during constant velocity or when the axis
stops. If the response time is poor, or the motion "sloppy" or slow, the
proportional gain may need to be increased. If excessive ringing or
overshoot is observed when the motor stops, the proportional gain may
need to be decreased.

The P gain may also be set based on the desired loop gain of the final
system. If you know the desired loop gain in inches per minute per mil
or millimeters per minute per mil, use the following formula to calculate
the corresponding P gain.

A loop gain of 1 inch per minute per mil (P gain = 0.0167) provides
stable positioning of virtually any axis.

If this axis uses a velocity loop servo amplifier and you are converting
it from a basic (IMC-S/20x) or integrated (IMC-S/21x) IMC S Class
motion controller, calculate the equivalent P gain for the IMC S Class
Compact (IMC-S/23x) using the formula below.

Continuing our example above, if a basic or integrated IMC S Class
had previously been used successfully on this axis with a P gain of
0.586, the equivalent P gain for the IMC S Class Compact is calculated
as shown below.

If this axis uses a torque loop servo amplifier and you are converting it
from a basic (IMC-S/20x) or integrated (IMC-S/21x) IMC S Class
motion controller, use the same P gain in the IMC S Class Compact
(IMC-S/23x) as was used in the basic or integrated controller.

Desired Loop Gain

InchesperMinute

Mil

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P gain =

Basic/Integrated P gain

Compact P gain =

Compact V gain

0.586

Compact P gain =

= 0.0195