Delta RMC101 - Manual (Page 244)

RMC100 and RMCWin User Manual
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Note how the target pressure begins rising immediately once the pressure reaches Pressure
Set A, causing the actual pressure to lag. Because of the short ramp time, the pressure
overshoots when it reaches the commanded pressure.
• To keep the pressure from lagging when entering pressure control in this case, the speed
entering pressure control can changed to closer match the axis speed once pressure control
has been entered. This will result in a smaller change in speed at the transition, and less
pressure lag.
• Currently, the entering speed is 1000 (1 in/sec, from Step 6, Speed field). If we change this to
10000 and run Event Step 1, the plot looks like this:
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The speed discontinuity upon the transition is much smaller. The speed can be further
changed if desired.
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The pressure still overshoots. The simplest solution for this is to use a longer ramp time. It
may be possible to further tune the system, but it is likely that the system response simply
can't handle such fast pressure changes.
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Lengthening the ramp time to 1000 msec (Step 4, Speed field), changing the Speed in Step 5
back to 1000 and running Event Step 1 results in the following plot: