CSDP Plus Servo Drive User Manual

When the position feedforward function is used, the speed command
varies highly in response to the change of position command.
Therefore, if the position command input fluctuates rapidly, in cases of
rapid acceleration or deceleration, feedforward can cause overshoot.
To reduce position command completion time in this case, raise the
value of the torque command filter (SEt-06) slowly and locate the
appropriate value. Or it may be desirable to restrain the high
frequency element of the position feedforward by using the speed
command filter (SEt-40) or soften the position command itself by using
the position command filter (SEt-35).
ATTENTION
Using online auto tuning and position feedforward function
together can make the system unstable.
Speed Bias Function
In the position control mode, another way to reduce position
completion time is to apply bias to speed command according to
position error. When this function is used, position error can be
reduced quickly as faster speed command is issued to reduce error at
the area with large position error. This has the same effect as a
relatively higher position proportional gain is applied to an area with
large position error, and by doing so, the position completion time
near the steady state can be reduced.
Please set the speed bias amount at SEt-38. The
setting range is 0 to 450 RPM and the default value
is 0. If the position error is bigger than the preset
value of the speed bias application range (SEt-39), a faster speed
command that includes the value of the speed command set here will
be issued.
Please set the speed bias application range at
SEt-39. The setting range is 0 to 250 pulse and the
default value is 10. When the position error is
bigger than the value set here, the speed bias amount (SEt-38) will be
added to the speed command.
If the absolute value of position error is bigger than the preset value of
the speed bias application range, the speed command equal to the
preset value of the speed bias amount will be added to the position
control output. Please adjust the speed bias amount and the speed
bias application range alternately while watching transient response. If
the speed bias amount is set too high or the speed bias application
range is set too low, vibration can occur.
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