Gain margin, phase margin, delay margin, and crossover frequencies

computes the gain margin, phase margin, delay margin, and the corresponding
crossover frequencies for the SISO or MIMO negative feedback loop with open-loop
response `S`

= allmargin(`L`

)`L`

. The negative feedback loop is computed as
`feedback(L,eye(M))`

, where `M`

is the number
of inputs and outputs in `L`

.

For a MIMO system, `allmargin`

returns loop-at-a-time stability
margins for the negative-feedback closed loop system. Use
`allmargin`

to find classical margins of any SISO or MIMO
model, including models with delays.

`allmargin`

assumes that the system with open-loop response`L`

is a negative-feedback system. To compute the classical stability margins of the positive feedback system`feedback(L,eye(M),+1)`

, use`allmargin(-L)`

.To compute classical margins for a system modeled in Simulink

^{®}, first linearize the model to obtain the open-loop response at a particular operating point. Then, use`allmargin`

to compute classical stability margins for the linearized system. For more information, see Stability Margins of a Simulink Model (Robust Control Toolbox).

Linear System Analyzer | `margin`

| `diskmargin`

(Robust Control Toolbox)

- Stability Margins of a Simulink Model (Robust Control Toolbox)