User guide

➃ Servo Tuning 39
Step 2
With SGP equal to 15, the response became
slightly underdamped (see plot).
Therefore, we should introduce the velocity
feedback gain (SGV) to damp out the
oscillation.
SGP = 15
Step 3
With SGV equal to 2, the response turn out
fairly well damped (see plot).
At this point, the SGP should be raised again
until oscillation or excessive overshoot
appears.
SGP = 15
SGV = 2
Step 4
As we iteratively increased SGP to 105,
overshoot and chattering became significant
(see plot). This meant either the SGV gain
was too low and/or the SGP was too high.
Next, we should try raising the SGV gain to
see if it could damp out the overshoot and
chattering.
SGP = 105
SGV = 2
Step 5
After the SGV gain was raised to 2.6, the
overshoot was reduced but chattering was
still quite pronounced. This meant either
one or both of the gains was too high.
The next step should be to lower the SGV
gain first.
SGP = 105
SGV = 2.6
Step 6
Lowering the SGV gain to 2.3 did not help
reduce the chattering by much.
Therefore, we should lower the SGP gain
until chattering stops.
SGP = 105
SGV = 2.3
Step 7
Chattering stopped after reducing the SGP
gain to 85. However, the overshoot was
still a little too high.
The next step should be to try raising the
SGV to damp out the overshoot.
SGP = 85
SGV = 2.3