Delta RMC151 - Manual (Page 59)

2 Starting Up the RMC
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.
Tip:
For a 2.5 in bore hydraulic cylinder with a max velocity of 30 in/sec, the
Proportional Gain is typically on the order of 20 to 300. Start with a small value.
• Click the Download button to apply the changes to the RMC.
10. Adjust the Integral Gain
Many hydraulic systems do not require a large Integral Gain. However, it is usually
desirable to have some Integral Gain 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. 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.
Tip:
Typically, the Integral Gain should be 3 to 5 times greater than the Proportional Gain.
• Click the Download button to apply the changes to the RMC.
Too little Integral Gain:
The system may not get into position very quickly, and it will take a long time to recover
from quick changes in the system, for example static friction, load changes, or obstacles.
Too much Integral Gain:
The system will begin oscillating.
Correct Integral Gain:
The system will get into position quickly, and any system changes will be quickly
corrected.
11. 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.
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. However, this can be compensated for by using the Output Filter. Systems that
are difficult to tune can sometimes be drastically improved by using the Output Filter
together with the Differential gain.
Many systems do not require any Differential Gain.
• Start with a small value of Differential Gain. Remember that it is a floating point
number, and you will may have to start with a number much smaller than 1,
depending on your system.
Tip:
For a 2.5 in bore hydraulic cylinder with a max velocity of 30 in/sec, the Differential
Gain, if any, is typically on the order of 0.01 to 2. Start with a small value.
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