Motion smoothing, Using the it and vt commands (s curve profiling) – Yaskawa LEGEND-MC User Manual

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LEGEND-MC User’s Manual

Motion Smoothing

The LEGEND-MC 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 (S curve profiling):

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, known as S curve, has continuous acceleration and results
in reduced mechanical vibrations.

The smoothing function is specified by the following commands:

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.

Note that the smoothing process results in longer motion time.

Command

Description

IT x,y

Independent time constant

VT n

Vector time constant

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