175
SV200 DC Hardware Manual
920-0126A
4/14/2017
11.3 Fine tuning
Depending on the mechanical system characteristics and the servo motor used, the following parameters are available and may need to
be adjusted to improve system performance:
●
Global gain (KP)
●
Position loop gain (KF)
●
Derivative gain (KD)
●
Damping gain (KV)
●
Integrator Gain (KI)
●
Inertia feed forward gain constant (KK)
●
Derivative filter gain (KE)
●
PID filters (KC)
This step should be completed only after the
Auto-Tune
function has been done and if improvements are needed for the tuning. A
sample move can be defined and run once for each click of the Start button or continuously to facilitate real-time dynamic tuning (i.e.
adjustment of gains and filter settings while the motor is moving).
Among the parameters listed above, changes to Global gain (
KP
), Derivative filter gain (
KE
) and PID filter (
KC
) are NOT
recommended after the system has been configured with the
Auto-Tune
function. Therefore, parameter adjustments during the fine
tuning phase should be limited to Position loop gain (
KF
), Derivative gain (
KD
), Damping gain (
KV
), Integrator Gain (
KI
), Inertia
feed forward gain constant (
KK
). See details below.
However, if you experience mechanical resonance or hear high-pitched squealing noises, you can lower the PID Output Filter below the
natural frequency of your system so that the PID output does not excite the resonance.
If you have a large inertial load, you’ll probably find that you (or the auto-tuner) need to set the gain parameters high, especially PP
and KI, to get good response. Then you will want to increase the damping to prevent ringing. Now the system is likely to be so tight
that if you have a springy, all metal coupling it may “buzz” or “squawk”. Reducing the frequency of the derivative filter can remove this
objectionable sound.
