5.9 Adjustments
constant. The filter, however, will produce a delay in the servo system, just like the integration
time constant, and its value should not be increased any more than necessary.
If the secondary torque reference filter time constant (Cn-0018) is set to 0, the torque reference
filter will be switched to the primary filter.
If the vibration cannot be overcome by the torque reference filter time constant (Cn-0017), use
the secondary torque reference filter time constant (Cn-0018) to switch the filter to the second-
ary filter and overcome the vibration.
■ Cn-001A: Position Loop Gain
The position loop gain determines the response of the servo system. The higher it is set, the higher
the response and the less time it takes for positioning. As such, the equipment must have higher
rigidity and a higher characteristic frequency.
The entire servo system is more susceptible to vibration if position loop gain alone is increased
to improve response, and the speed reference output from the position loop will cause vibration.
Always increase speed loop gain while checking the response.
Position loop gain Kp is calculated as shown below.
V s
IC p = 7
14 (1/s): Position loop gain
V, (PPS): Steady speed reference
e (Pulse): Steady error (The number of pulses in the error counter at constant speed)
• Adjustment
Follow the procedure below to make adjustment.
1. Calculate and set the motor axis converted load inertia.
2. Set the loop gain to a low value and increase speed loop gain within a range that does not
cause noise or vibration to occur.
3. Slightly reduce the speed loop gain from the value in step 1, and increase position loop gain
within a range that does not cause overshooting or vibration to occur.
4. Determine the speed loop integration time constant by observing the positioning time and
vibration in the mechanical system. Positioning time may be increased if the speed loop in-
tegration time constant is too large.
5. It is not necessary to change the torque reference filter time constant unless torsional reso-
nance occurs in the equipment shafts. Torsion resonance may be present if there high-fre-
quency vibration noise. In this case, adjust the torque reference filter time constant to reduce
the noise.
6. Finally, it is necessary to determine the optimum value for acceleration/deceleration to ad-
just finely the position and speed loop gain as well as the integration time constant.
• Monitoring
The MECHATROLINK communication monitoring function can be used to read various
monitors, display the monitor status at the host controller, and make any necessary adjustments.
5 -21
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