Motion Smoothing; Using The It And Vt Commands - Galil Motion Control DMC-14 5 Series Manual

Motion Smoothing

The DMC-14XX controller allows the smoothing of the velocity profile to reduce mechanical
vibrations in 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

When operating with servo motors, motion smoothing can be accomplished with the IT and VT
commands. These commands filter the acceleration and deceleration functions to produce a smooth
velocity profile. The resulting velocity profile, has continuous acceleration and results in reduced
mechanical vibrations.
The smoothing function is specified by the following commands:
IT x,y
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 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. 6.7 shows the trapezoidal velocity
profile and the modified acceleration and velocity.
Note that the smoothing process results in longer motion time.
Example - Smoothing
Instruction
PR 20000
AC 100000
DC 100000
SP 5000
IT .5
BG X
DMC-14x5/6
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Independent time constant
Vector time constant
Interpretation
Position
Acceleration
Deceleration
Speed
Filter value
Begin
Chapter 6 Programming Motion 85
i