Package: TuningGoal
Overshoot constraint for control system tuning
Use the TuningGoal.Overshoot
object to limit
the overshoot in the step response from specified inputs to specified
outputs of a control system. Use this requirement for control system
tuning with tuning commands such as systune
or looptune
.
creates
a tuning requirement 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 requirement
cannot reliably reduce the overshoot below 5%.

Input signals for the requirement, specified as a string or as a cell array of strings, for multipleinput requirements. If you are using the requirement to tune a Simulink^{®} model
of a control system, then
If you are using the requirement to tune a generalized statespace
(
For example, if you are tuning a control system model, If
For more information about analysis points in control system models, see Marking Signals of Interest for Control System Analysis and Design. 

Output signals for the requirement, specified as a string or as a cell array of strings, for multipleoutput requirements. If you are using the requirement to tune a Simulink model
of a control system, then
If you are using the requirement to tune a generalized statespace
(
For example, if you are tuning a control system model, If
For more information about analysis points in control system models, see Marking 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);


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 tuning 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 strings. These
strings specify the names of the inputs of the transfer function that
the tuning requirement constrains. The initial value of the 

Output signal names, specified as a cell array of strings. These
strings specify the names of the outputs of the transfer function
that the tuning requirement constrains. The initial value of the 

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

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

Name of the requirement object, specified as a string. For example, if Req.Name = 'LoopReq'; Default: 
When you use a TuningGoal
object to specify
a tuning requirement, the software converts the requirement 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 requirement 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 requirement 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%.