Chapter 2 RobustnessAnalysis
© National Instruments Corporation 2-7 MATRIXx Xmath Robust Control Module
Figure 2-5. Stability Margin
Now examine the effect on the stability margin of discretizing H(s) at
100 Hz.
dt = 0.01;
Hd = discretize(H,dt);
margD = smargin(Hd,delb);
smargin --> Scaling algorithm is type: PF
smargin --> Margin computation 10% complete
smargin --> Margin computation 50% complete
smargin --> Margin computation 90% complete
100 Hz is a high discretization frequency for H, so the stability margin
is unchanged in the discrete-time case. The new plot is not much
different from Figure2-6. A gain, minimum margin is about 8 dB
atabou t 1/2 Hz.