Appendix A
87
Tuning Scenario
This example shows how to obtain the highest possible proportional feedback (SGP) and
velocity feedback (SGV) gains experimentally by using the flow diagram illustrated earlier in
Step 5 of the Tuning Procedure.
NOTE
The steps shown below (steps 1 - 11) represent the major steps of the process; the actual
progression between these steps usually requires several iterations.
The motion command used for this example is a step command with a step size of 100. The
plots shown are as they appear in Motion Architect’s Controller Tuner Module (X axis = time,
Y axis = position).
Step 1
For a starting trial, we set the proportional
feedback gain (SGP) to 2. As you can see
by the plot, the response is slow.
In the next step, we should increase SGP
until the response is slightly underdamped.
SGP = 2
Commanded Position
Actual Position
Step 2
With SGP equal to 15, the response becomes
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 turns 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 increase SGP to 105,
overshoot and chattering becomes significant
(see plot). This means either the SGV gain
is too low and/or the SGP is 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
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