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Sigma II User’s Manual Chapter 6: Servo Adjustment
6 - 35
6.4.3 Making Manual Adjustments
The auto-tuning function uses a gain adjustment algorithm with a comparatively
large safety margin by considering a variety of mechanical systems to which the
servo amplifier is applied. Therefore, the servo amplifier may not satisfy the
response characteristics of some applications. The auto-tuning function is not
available to machines with low rigidity or high fluctuation.
In such cases, observe the mechanical systems and make manual adjustments of
parameters.
Speed Control
Required Parameters
The following parameters are used.
• Speed Loop Gain (Pn100)
This parameter is used for determining the responsiveness of the speed loop. For
the best response, set this parameter as high as possible, without exceeding the
point where the mechanical system vibrates. The value of speed loop gain is the
same as the set value of Pn100 if the inertia ratio set in Pn103 is correct.
Speed loop gain Kv = Set value of Pn100 (Hz)
Set Pn103 to the following value.
Note: In the case of manual adjustments of parameters, the user must set the value of parameter Pn103. The
inertia ratio can be obtained if the servo gain constant is written with parameter Fn007 after auto-tun-
ing has been performed. For details regarding Fn007, refer to
6.3 Auto-Tuning.
• Speed Loop Integral Time Constant (Pn101)
The speed loop has an integral element so that the speed loop can respond to
minute inputs. This integral element delays the operation of the servo system,
resulting in a longer positioning settling time. As the value of the time constant
increases, the response becomes slower. If the load inertia is large or the
mechanical system is likely to vibrate, make sure that the speed loop integral
time constant is large enough. Use the following formula to calculate the opti-
mum integral time constant.
Where: T
i
= Integral time constant [s]
K
v
= Speed loop gain (calculated from the above) [Hz]
Pn103 Setting Value =
×
100%
Motor load inertia (J
L
)
Servomotor rotor inertia (J
M
)
T
i
≥
2.3
×
1
2π ×
K
v