Yaskawa FSP Amplifier - Manual (Page 185)

FSP Amplifier User’s Manual Chapter 6: Servo Adjustment
6-18
6.3.6. Flexible System Parameters
• K
ff
Spring (Pn1BB) range 10 to 2000 [Hz] default 2000:
This parameter compensates the position error during the acceleration
and deceleration phase and the overshoot observed when stopping at the
end of a deceleration phase. Typically, this overshoot is caused by the
elasticity of the system; a wind up occurs during the deceleration phase
and relaxes after stop. The K
ff
Spring parameter compensates for that
wind up.
The frequency of this parameter relates to the self-oscillation frequency
of the system. It can be adjusted to avoid overshoot and minimize
settling time.
Default value is 2000 Hertz. This value is well beyond the frequency
response of usual systems, so that it has no influence.
To adjust, decrease this value progressively, while monitoring the
position error, until overshoot is canceled or position error in the
acceleration and deceleration phase are minimized.
• KfbSpring (Pn1BD) range 10 to 2000 [Hz] default 2000:
This parameter compensates the vibrations of the motor, it smoothes the
control in case of a flexible system. Usually it should be tuned to the
low resonance of the system.
You can tune this parameter by progressively decreasing its value until
vibrations occur. Then use a higher value for setting (~20%).
6.3.7. Gain Factor
• Tightness (Pn1A0), Range 0 to 500 [%], Default 60:
This parameter changes the frequencies of feedback parameter linearly,
keeping their relative ratio, so that system rigidity can be changed
without getting unstable. A good starting value is 60%.
After setting the default values for load, one can increase or decrease
the stiffness of the servo control by changing this parameter.
This can be done while monitoring the position error during the
movement and thus choosing the optimal value for the system
application.