Delta RMC101 User Manual
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RMC100 and RMCWin User Manual
7-4
oscillate around the set point as the RMC overshoots first in one direction, then the other.
Hoses
Long hoses between the valves and cylinder act as accumulators and make the system respond
as if it has a spring in it (imagine trying to control the position of one end of a Slinky™ by moving
the other end!). The lines between the valves and cylinders must be as short and rigid as
possible.
Pumps and Accumulators
Insufficient pump and/or accumulator capacity will cause the system response to degrade during
a move because the effective pressure drops.
Pressure transients due to insufficient accumulator volume cause jerky motion, particularly during
starts and stops.
Note:
Even systems with ’r;fast’ pumps usually require at least a small accumulator near the
cylinder to maintain the constant pressure needed to get smooth motion.
Insufficient pump capacity can result in inadequate control when moving many axes
simultaneously or when making long moves. In these cases pressure can drop so much a fully
open valve cannot maintain the requested speed.
Identification and Correction
To identify and correct these problems, make a move with very low (or zero) gains except the
Feed Forward terms. Graph the move. The graph (ignoring the Position terms) should show:
If the actual speed and target speed show: