ADLINK Technology PCI-8154, User Manual

Page: 56 / 228

46 Operation Theory
4.2.4 S-curve and Bell-curve speed profile
S-curve means the speed profile in accelerate/decelerate area fol-
lows a 2nd order curve. It can reduce vibration at the beginning of
motor start and stop. In order to speed up the acceleration/decel-
eration during motion, we need to insert a linear part into these
areas. We call this shape as “Bell” curve. It adds a linear curve
between the upper side of s-curve and lower side of s-curve. This
shape improves the speed of acceleration and also reduces the
vibration of acceleration.
For a bell curve, we define its shape parameters as below:
X
Tacc: Acceleration time in second
X Tdec: Deceleration time in second
X
StrVel: Starting velocity in PPS
X MaxVel: Maximum velocity in PPS
X
VSacc: S-curve part of a bell curve in deceleration in PPS
X VSdec: S-curve part of a bell curve in deceleration in PPS