Introduction To Feed Shaft Servo Gain Adjustment - YASKAWA SGD7S series Product Manual

6.1 Introduction to Feed Shaft Servo Gain Adjustment

6.1

Introduction to Feed Shaft Servo Gain Adjustment

To adjust the feed shaft servo gains, we recommend that you use custom tuning and prioritize
stable high-speed high-precision trajectory tracking.
The following servo gains are adjusted with a position reference or speed reference input from
the host controller while the machine is in operation.
• Gains (e.g., speed loop gain and position loop gain)
• Filters (torque reference filter and notch filters)
• Anti-resonance control
If you perform the above servo gain adjustments, the effects given in the following table will
occur. Adjust the gains while checking for these effects.
Items Affected by Servo
Gain Adjustment
Servo gain adjustment
(vibration limit servo gains)
Servo gains for allowable
torque ripple at constant
speed
Other items to check
Set the tuning level for the servo gains (speed loop gain and position loop gain) to the smaller
of the following two values to provide a leeway in stability.
• 70% to 80% of the vibration limit servo gain
• Servo gains for allowable torque ripple at constant speed
To prevent distortion in arcs and other interpolation trajectories for the feed shaft in a cutting
application, the interpolation shafts must all have the same tuning level.
Therefore, you must change the tuning levels of other interpolation shafts so that they are the
same as any shaft with a low tuning level.
Check the other check items in the above table at the final tuning level to complete the adjust-
ments.
The tuning level must be set to between 40 and 100.
6-2
Adjustment Methods
• Check the vibration limit of vibration resulting from high servo gains. For
suppressible vibrations, apply the vibration suppression functions of the
SERVOPACK as necessary.
• Check the tuning level when vibrations cannot be suppressed.
The torque ripple (which results in vibration) at constant speed must not
be great. As a guideline for the allowable range, make sure that the servo
gain maintains the torque ripple within 5% of the rated torque.
• Extreme overshooting must not occur during acceleration or decelera-
tion.
• Torque must not become saturated during acceleration or deceleration.
• Acceleration/deceleration time
• There must be no fluctuation in the speed when operating at a constant
speed.