Specifications

10 Design Case Studies
10-28
step(cloop)
Thisresponsedependsonyourclosedloopsetpoint.Theoneshownhereis
relatively fastandsettles inabout 0.07 seconds. Therefore,thisclosedloopdisk
drive system has a seek time of about 0.07 seconds. This is slow by today's
standards, but you also started with a very lightly damped system.
Now look at the robustness of your design. The most common classical
robustnesscriteriaare the gain and phase margins. Use the function
margin to
determinethesemargins.Withoutputarguments,
margin returnsthegainand
phase margins as well as the corresponding crossover frequencies. Without
output argument,
margin plots the Bode response and displays the margins
graphically.
To compute the margins, first formthe unity-feedback open loop by connecting
the compensator , plant model, and feedback gain in series.
olk = K * oloop;
Dz() k