Galil Motion Control DMC-4123 - Motion Smoothing; Using the IT Command; Example - Smoothing

The design approach is to drive the motor a distance, which corresponds to 40,000 rotary counts. Once the
motion is complete, the controller monitors the position of the linear encoder and performs position corrections.
This is done by the following program.
INSTRUCTION INTERPRETATION
#DUALOOP
Label
CE 0
Configure encoder
DE0
Set initial value
PR 40000
Main move
BGX
Start motion
#correct
Correction loop
AMX
Wait for motion completion
V1=10000-_DEX
Find linear encoder error
V2=-_TEX/4+V1
Compensate for motor error
JP#END,@ABS[V2]<2
Exit if error is small
PR V2*4
Correction move
BGX
Start correction
JP#correct
Repeat
#END
EN
Motion Smoothing
The DMC-41x3 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 Command:
When operating with servo motors, motion smoothing can be accomplished with the IT command.
This command filters 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,z,w
Independent time constant
The command, IT, is used for smoothing independent moves of the type JG, PR, PA and 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. Figure 6.20 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
Position
AC 100000
Acceleration
DC 100000
Deceleration
SP 5000
Speed
IT .5
Filter for smoothing
BG X
Begin
Chapter 6 Programming Motion ▫ 97 DMC-41x3 User Manual