Chapter 4
4-19
Operation
• Adjust the position loop response to suit the mechanical rigidity of the system.
• Servo system response is determined by the position loop gain. Servo systems with a high loop
gain have a high response, and positioning is fast. To increase the position loop gain, you must
improve mechanical rigidity and increase the specific oscillation. This should be 50 to 70 (1/s) for
ordinary machine tools, 30 to 50 (1/s) for general-use and assembly machines, and 10 to 30 (1/s)
for production robots. The default position loop gain is 40 (1/s), so be sure to lower the setting for
machines with low rigidity.
• Raising the position loop gain in systems with low mechanical rigidity or systems with low specific
oscillation may result in machine resonance, causing an overload alarm to occur.
• If the position loop gain is low, you can shorten the positioning time using feed forward. You can
also shorten the positioning time using the bias function.
• Position loop gain is generally expressed as follows.
When the position loop gain is manipulated, the response is as shown in the following diagram.
Note This parameter is enabled only if the gain adjustment rotary switch has been set to 0.
• Set the mechanical system inertia (load inertia for Servomotor shaft conversion) using the ratio (%)
of the Servomotor rotor inertia. If the inertia ratio is set incorrectly, Pn100 (speed loop gain) will also
be incorrect.
• This parameter is the initial online autotuning value. After performing online autotuning, the correct
value will be written to Pn103 if the tuning results are saved. Refer to 4-5-1 Online Autotuning for
details.
Pn102
Position loop gain
Settings
1 to 2000
Unit
1/s
Default
40
Restart?
---
Pn103
Inertia ratio
Settings
0 to 10000
Unit
%
Default
300
Restart?
---
Position loop gain (Kp) = (1/s)
Command pulse frequency (pulses/s)
Deviation counter residual pulses (pulses)
Servomotor speed
Time
When position loop gain is high.
When position loop gain is low.
Summary of Contents for SMARTSTEP A Series
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