
B-65150E/04 4. SERVO FUNCTION DETAILS
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(For those who want to know details)
The observer estimates a disturbance torque by subtracting the torque
required for acceleration/deceleration from the entire torque. The
torque required for acceleration/deceleration is calculated using a
motor model. The POA1 parameter corresponds to the inertia of the
motor model. If the parameter value differs from the actual value, it is
impossible to estimate a correct disturbance torque. To detect an
abnormal load correctly, therefore, you must adjust the value of this
parameter.
An estimated disturbance value when a usual condition is supposed to
be related only to frictional torque (for the horizontal axis), and
proportional to the velocity. Therefore, a program, like the one used
for adjustment, that merely repeats simple acceleration/deceleration is
supposed to generate a trapezoidal estimated disturbance torque
waveform like a velocity waveform.
NOTE
The POA1 parameter is related to the load inertia ratio
parameter ("velocity gain" on the servo screen)
through the inside of the software. When the load
inertia ratio parameter is changed, the POA1
parameter must also be changed. So, first determine
the load inertia ratio (velocity gain) when adjusting the
servo.
If you must change the load inertia ratio (velocity gain)
after the POA1 parameter is determined, re-set the
POA1 parameter using the following expression.
(New POA1 value)
= (Previous POA1 value) ×
Load inertia ratio value set after adjustment + 256
Load inertia ratio value set before adjustment + 256
= (Previous POA1 value) ×
Velocity gain set after adjustment (%)
Velocity gain set before adjustment (%)