Delta RMC101 - Manual (Page 47)

RMC100 Startup Appendix B: Tuning
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movement. The Acceleration Feed Forward terms can help compensate for this
delay.
Look for following errors during acceleration and deceleration. Increase the
Extend and Retract Acceleration Feed Forward terms until the errors disappear.
For large masses the Acceleration Feed Forward may be in the tens of
thousands.
7. Readjust the Proportional Gain
Proportional Gain affects the responsiveness of the system. Low gains make
the system sluggish and unresponsive. Gains that are too high make the axis
oscillate or vibrate.
Slowly increase the gain. When you see a tendency to oscillate as the axis
moves or stops, reduce the gain by 10 to 30 percent.
At this point, if you have gained sufficient control of the system, you may want
to increase the speed, accel and decel of your moves and further adjust the
proportional gain. A value of proportional gain that may seem good at low
speeds and accels, may not work at higher speeds.
8. Adjust the Integral Gain
The Integral Gain is helpful for getting into position and for tracking during
long, slow moves. It will not significantly affect tracking during short, fast
moves. Many hydraulic systems do not require a large Integral Gain. However,
it is usually desirable to have some Integral Gain (5 to 50 units) to help
compensate for valve null drift or changes in system dynamics. Some systems
may require larger Integral Gain, in particular if they are moving a large mass
or are nonlinear. Too much Integral Gain will cause oscillations and overshoot.
9. Adjust the Differential Gain
Differential Gain may greatly enhance performance on many hydraulic
systems. It is used mainly on systems that have a tendency to oscillate. This
happens when heavy loads are moved with relatively small cylinders.
Differential Gain will tend to dampen out oscillations and help the axis track
during acceleration and deceleration. This will positively affect short, fast
moves.
Important: If you use Differential Gain, you may be able to increase the
Proportional Gain somewhat without causing the system to oscillate.
If the drive output during the constant velocity portion of the move is smooth,
the Differential Gain is perhaps not set high enough. The drive output may
look "fuzzy." This indicates that the drive is responding to the minute errors of
the axis. Note that not all systems allow the differential gain to be set high
enough for the drive to be "fuzzy".
A disadvantage of Differential Gain is that it amplifies position measurement
noise. If there is too much noise or the gain is too high, this can cause the
system to chatter or oscillate.
10. Increase System Speed
Gradually increase the Speed and Acceleration values while making long
moves. Look for following errors, overshoot, or oscillations.
• If an overdrive error occurs, there is not enough drive capacity to drive the
axis at the requested Speed or Acceleration. Should this occur, reduce the
Speed and/or Acceleration and Deceleration.