Simulink Control Design™ - MathWorks

Algorithm

The gain and phase margin values are both derived from the disk margin. The disk

margin measures the radius of a circular exclusion region centered near the critical point.

(See “Stability Analysis Using Disk Margins” (Robust Control Toolbox).) This radius is a

decreasing function of the scaled norm:

min

Ddiagonal

D−^1 I−Ljω I+Ljω −^1 D 2.

Unlike the traditional gain and phase margins, the disk margins and associated gain and

phase margins guarantee that the open-loop response L(jω) stays at a safe distance from

the critical point at all frequencies.

See Also

TuningGoal.Margins | diskmargin

More About

• “Loop Shape and Stability Margin Specifications” on page 13-42


• “Margins Goal” on page 10-147


• “Stability Analysis Using Disk Margins” (Robust Control Toolbox)

10 Control System Tuning