Yaskawa SMC–4000 - Manual (Page 300)

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SMC–4000 User Manual
Motion Smoothing
The SMC–4000 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 (Independent Time Constant) and VT (Vector Time Constant) 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 an 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.
Stepper Motor Operation
When confirgured for stepper motor operation, several commands are interpreted differently than from
servo mode. The following describes operation with stepper motors. Jumpers must be internally installed
at position CN5 on the power board.
Specifying Stepper Motor Operation
In order to command stepper motor operation, the appropriate stepper mode jumpers must be installed.
Stepper motor operation is specified by the command MT. The argument for MT is as follows:
2Specifies a stepper motor with active low step output pulses.
-2Specifies a stepper motor with active high step output pulses.
2.5Specifies a stepper motor with active low step output pulses and reversed direction.
-2.5Specifies a stepper motor with active high step output pulses and reversed direction.
Command Description
IT x,y Independent time constant
VT n Vector time constant