TuningGoal.Overshoot class
Package: TuningGoal
Overshoot constraint for control system tuning
Description
Use TuningGoal.Overshoot
to limit the overshoot
in the step response from specified inputs to specified outputs of
a control system. Use this tuning goal for control system tuning with
tuning commands such as systune
or looptune
.
Construction
creates
a tuning goal for limiting the overshoot in the step response between
the specified signal locations. The scalar Req
= TuningGoal.Overshoot(inputname
,outputname
,maxpercent
)maxpercent
specifies
the maximum overshoot as a percentage.
When you use TuningGoal.Overshoot
for tuning,
the software maps overshoot constraints to peak gain constraints assuming
secondorder system characteristics. Therefore, the mapping is only
approximate for higherorder systems. In addition, this tuning goal
cannot reliably reduce the overshoot below 5%.
Input Arguments

Input signals for the tuning goal, specified as a character vector or, for multipleinput tuning goals, a cell array of character vectors.
For more information about analysis points in control system models, see Mark Signals of Interest for Control System Analysis and Design. 

Output signals for the tuning goal, specified as a character vector or, for multipleoutput tuning goals, a cell array of character vectors.
For more information about analysis points in control system models, see Mark Signals of Interest for Control System Analysis and Design. 

Maximum percent overshoot, specified as a scalar value. For
example, the following code specifies a maximum 5% overshoot in the
step response from Req = TuningGoal.Overshoot('r','y',5);

Properties

Maximum percent overshoot, specified as a scalar value. For
example, the scalar value 5 means the overshoot should not exceed
5%. The initial value of the 

Reference signal scaling, specified as a vector of positive real values. For a MIMO tracking requirement, when the choice of units results in a mix of small and large signals in different channels of the response, use this property to specify the relative amplitude of each entry in the vectorvalued step input. This information is used to scale the offdiagonal terms in the transfer function from reference to tracking error. This scaling ensures that crosscouplings are measured relative to the amplitude of each reference signal. For example, suppose that Req.InputScaling = [100,1]; This tells the software to take into account that the first reference signal is 100 times greater than the second reference signal. The default value, Default: 

Input signal names, specified as a cell array of character
vectors that identify the inputs of the transfer function that the
tuning goal constrains. The initial value of the 

Output signal names, specified as a cell array of character
vectors that identify the outputs of the transfer function that the
tuning goal constrains. The initial value of the 

Models to which the tuning goal applies, specified as a vector of indices. Use the Req.Models = 2:4; When Default: 

Feedback loops to open when evaluating the tuning goal, specified as a cell array of character vectors that identify loopopening locations. The tuning goal is evaluated against the openloop configuration created by opening feedback loops at the locations you identify. If you are using the tuning goal to tune a Simulink model
of a control system, then If you are using the tuning goal to tune a generalized statespace
( For example, if Default: 

Name of the tuning goal, specified as a character vector. For example, if Req.Name = 'LoopReq'; Default: 
Examples
Tips
This tuning goal imposes an implicit stability constraint on the closedloop transfer function from
Input
toOutput
, evaluated with loops opened at the points identified inOpenings
. The dynamics affected by this implicit constraint are the stabilized dynamics for this tuning goal. TheMinDecay
andMaxRadius
options ofsystuneOptions
control the bounds on these implicitly constrained dynamics. If the optimization fails to meet the default bounds, or if the default bounds conflict with other requirements, usesystuneOptions
to change these defaults.
Algorithms
When you tune a control system using a TuningGoal
,
the software converts the tuning goal into a normalized scalar value f(x). x is
the vector of free (tunable) parameters in the control system. The
software then adjusts the parameter values to minimize f(x),
or to drive f(x) below 1 if
the tuning goal is a hard constraint.
For TuningGoal.Overshoot
, f(x)
reflects the relative satisfaction or violation of the goal. The percent
deviation from f(x) = 1 roughly
corresponds to the percent deviation from the specified overshoot
target. For example, f(x) =
1.2 means the actual overshoot exceeds the target by roughly 20%,
and f(x) = 0.8 means the actual
overshoot is about 20% less than the target.
TuningGoal.Overshoot
uses $${\Vert T\Vert}_{\infty}$$ as
a proxy for the overshoot, based on secondorder model characteristics.
Here, T is the closedloop transfer function that
the tuning goal constrains. The overshoot is tuned in the range from
5% ($${\Vert T\Vert}_{\infty}$$ =
1) to 100% ($${\Vert T\Vert}_{\infty}$$). TuningGoal.Overshoot
is
ineffective at forcing the overshoot below 5%.
Compatibility Considerations
See Also
looptune
 systune
 systune
(for slTuner)
(Simulink Control Design)  looptune (for slTuner)
(Simulink Control Design)  viewGoal
 evalGoal
 TuningGoal.Gain
 TuningGoal.Sensitivity
 slTuner
(Simulink Control Design)