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100 • Chapter 6 Programming Motion DMC-3425
PR v
2
*4 Correction move
BGA Start correction
JP#CORRECT Repeat
#END
EN
Motion Smoothing
The DMC-3425 controller allows the smoothing of the velocity profile to reduce the mechanical
vibration of the system.
Trapezoidal velocity profiles have acceleration rates that 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
command. 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 a Independent time constant
VT n Vector time constant
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 parameter a 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
Instruction
Interpretation
PR 20000 Position
AC 100000 Acceleration
DC 100000 Deceleration
SP 5000 Speed
IT .5 Filter for smoothing
BG A Begin