Delta MMC120 User Manual
Page 71
71
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 ‘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:
Your valve probably has overlap. Replace the valve with a linear one or try increasing
the
DEAD BAND ELIMINATOR
value.