| Using the SISO Design Tool and the LTI Viewer | |
Example: Adding a Closed-Loop Peak Gain Constraint
This example shows how to add a closed-loop peak gain constraint to the Nichols plot. First, type
This opens the SISO Design Tool with Gservo imported as the plant. Use the right-click menu to add a grid, as this figure shows.
To add closed-loop peak gain of 1 dB at -180 degrees, open the New Constraint editor and select Closed-Loop Peak Gain from the pull-down menu. Set the peak gain field to 1 dB. The figure shows the resulting design constraint; use Zoom X-Y to zoom in on the plot for clarity.
As long as the curve is outside of the shaded region, the closed-loop gain is guaranteed to be less than 1 dB. Note that this is equivalent, up to second order, to specifying the peak overshoot in the time domain. In this case, a 1 dB closed-loop peak gain corresponds to an overshoot of 15%.
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