Graphically analyze MIMO feedback loops
loopview(G,C)
loopview(G,C,info)
loopview(
plots
characteristics of the following positivefeedback, multiinput, multioutput
(MIMO) feedback loop with plant G
,C
)G
and controller C
.
Use loopview
to analyze the performance
of a tuned control system you obtain using looptune
.
Note:
If you are tuning a Simulink^{®} model with 
loopview
plots the singular values of:
Openloop frequency responses G*C
and C*G
Sensitivity function S = inv(1G*C)
and
complementary sensitivity T = 1S
Maximum (target), actual (tuned), and normalized MIMO
stability margins. loopview
plots the multiloop
disk margin (see loopmargin
).
Use this plot to verify that the stability margins of the tuned system
do not significantly exceed the target value.
For more information about singular values, see sigma
.
loopview(
uses
the G
,C
,info
)info
structure returned by looptune
. This syntax also plots the
target and tuned values of tuning constraints imposed on the system.
Additional plots include:
Singular values of the maximum allowed S
and T
.
The curve marked S/T Max
shows the maximum allowed S
on
the lowfrequency side of the plot, and the maximum allowed T
on
the highfrequency side. These curves are the constraints that looptune
imposes
on S
and T
to enforce the
target crossover range wc
.
Target and tuned values of constraints imposed by
any tuning goal requirements you used with looptune
.
Use loopview
with the info
structure
to assist in troubleshooting when tuning fails to meet all requirements.

Numeric LTI model or
tunable You can obtain 

You can obtain 


For analyzing Simulink models tuned with looptune
through
an slTuner
interface, use loopview
for slTuner
(requires Simulink Control Design).
looptune
 looptune
(for slTuner)
 loopview (for slTuner)
 slTuner