Delta RMC101 User Manual
Page 42
RMC100 and RMCWin User Manual
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• A disadvantage of Differential Gain is that it amplifies measurement noise. If there is too
much noise or the gain is too high, this can cause the system to chatter or oscillate. In this
case, decrease the Differential Gain.
7. Readjust the Proportional Gain
Once the Differential Gain has been adjusted, the Proportional Gain may be readjusted. It 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.
• Continue ramping between two pressures.
• Slowly increase the gain. When you see a tendency to oscillate as the pressure changes or
stops, reduce the gain by 10 to 30 percent.
8. Tune the Transition.
Now that both the position and pressure gains have been tuned, the transition may be tuned.
• Use the Event Step sequence to transition from position to pressure.
• If necessary, adjust the previously tuned pressure parameters for a smoother transition.
• If there is oscillation and overshoot or other undesirable behavior at the transition that
cannot be avoided with tuning the gains, the Ramp Time may need to be changed, or the
speed going into the transition may be need to be slower.
• Selecting Calculate Ramp Time in the Mode word allows the RMC to automatically
calculates the Ramp Time. This is useful if it is difficult to determine a Ramp Time.
• The following three steps also address parameters affecting the transition.
9. Adjust the Feed Forwards
The Extend and Retract Feed Forwards provide extra drive when extending or retracting.
• Adjust the Feed Forwards to help the actual pressure track the target pressure when it is
changing.
• If the actual pressure leads the target pressure, decrease the Feed Forwards.
• The Feed Forwards may need to change for different rates of pressure change. See Feed
Forwards for more information.
10. Integrator Preload
Upon transition from position control to pressure control, the drive normally goes immediately
toward zero. In some cases, this is undesirable. The integrator preload can be set to some value
(positive or negative) to provide some drive immediately upon the transition. If your system
overshoots or undershoots when entering pressure control, you may want to adjust this value.
See Integrator Preload for more information.