Motion Smoothing; Using The It And Vt Commands (S Curve Profiling) - Galil Motion Control DMC-1600 Series User Manual

Motion Smoothing

The DMC-1600 controller allows the smoothing of the velocity profile to reduce the mechanical
vibration of the system.
Trapezoidal velocity profiles have acceleration rates which change abruptly from zero to
maximum value. The discontinuous acceleration results in jerk which causes vibration. The
smoothing of the acceleration profile leads to a continuous acceleration profile and reduces the
mechanical shock and vibration.

Using the IT and VT Commands (S curve profiling):

When operating with servo motors, motion smoothing can be accomplished with the IT and VT
command. These commands filter the acceleration and deceleration functions to produce a smooth
velocity profile. The resulting velocity profile, known as S curve, has continuous acceleration and
results in reduced mechanical vibrations.
The smoothing function is specified by the following commands:
IT x,y,z,w
VT n
The command, IT, is used for smoothing independent moves of the type JG, PR, PA and the
command, VT, is used to smooth vector moves of the type VM and LM.
The smoothing parameters, x,y,z,w and n are numbers between 0 and 1 and determine the degree
of filtering. The maximum value of 1 implies no filtering, resulting in trapezoidal velocity
profiles. Smaller values of the smoothing parameters imply heavier filtering and smoother moves.
The following example illustrates the effect of smoothing. Fig. 6.8 shows the trapezoidal velocity
profile and the modified acceleration and velocity.
Note that the smoothing process results in longer motion time.
Example - Smoothing
PR 20000
AC 100000
DC 100000
SP 5000
IT .5
BG X
110 • Chapter 6 Programming Motion
Independent time constant
Vector time constant
Position
Acceleration
Deceleration
Speed
Filter for S-curve
Begin
DMC-1600