
B-65270EN/05 4.SERVO FUNCTION DETAILS
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1862 (FS15i)
Observer coefficient (POK1)
2050 (FS30i, 16i)
• When HRV1, HRV2, or HRV3 is used:
[Setting value] Usually, use the standard setting.
• When HRV4 is used:
[Setting value] 956 → To be changed to 264
1863 (FS15i)
Observer coefficient (POK2)
2051 (FS30i, 16i)
• When HRV1, HRV2, or HRV3 is used:
[Setting value] Usually, use the standard setting.
• When HRV4 is used:
[Setting value] 510 → To be changed to 35
(5) Note
The parameter is initially set to such a value (standard setting) that the
cutoff frequency of the filter becomes 30 Hz. With this setting, the
effect of filtering becomes remarkable at resonance frequencies above
the range of 150 Hz to 180 Hz.
To change the cutoff frequency, set parameters POK1 and POK2 to a
value listed below, while paying attention to Table 4.5.4:
Generally, the observer function does not work unless its cutoff
frequency is held below Fd/5 or Fd/6, where Fd is the frequency
component of an external disturbance. However, if this bandwidth is
some 20 Hz or lower, the velocity loop gain also drops or becomes
unstable, possibly causing a fluctuation or wavelike variation.
Table 4.5.4 Changing the observer cutoff frequency
HRV1,HRV2,HRV3 HRV4
Cutoff frequency (Hz)
POK1 POK2 POK1 POK2
10 348 62 90 4
20 666 237 178 16
30 956 510 264 35
40 1220 867 348 62
50 1460 1297 430 96
60 1677 1788 511 136
70 1874 2332 1874 183
(6) Setting observer parameters when the unexpected disturbance torque
detection function is used
The unexpected disturbance torque detection function (see Sec. 4.12)
uses the observer circuit shown in Fig. 4.5.4 (b) to calculate an
estimated disturbance. In this case, to improve the speed of calculation,
change the settings of observer parameters POA1, POK1, and POK2
by following the explanation given in Sec. 4.12.
When the observer function and unexpected disturbance torque
detection function are used together, however, the defaults for POK1
and POK2 must be used.