sdo.requirements.SignalTracking
Reference signal to track
Description
Specify a tracking requirement on a time-domain signal. You
can then optimize the model response to track the reference using sdo.optimize
.
You can specify an equality, upper bound, or lower bound requirement.
Creation
Syntax
Description
creates an
track_req
= sdo.requirements.SignalTrackingsdo.requirements.SignalTracking
object and assigns default values to its properties.
specifies one
or more properties using name-value arguments. For
example, track_req
=
sdo.requirements.SignalTracking(Name=Value)track_req =
sdo.requirements.SignalTracking(Type=">=")
creates an sdo.requirements.SignalTracking
object and specifies the Type
property as
a lower bound.
Before R2021a, use commas to separate each name and value, and enclose
Name
in quotes. For example, track_req =
sdo.requirements.SignalTracking("Type",">=")
creates an
sdo.requirements.SignalTracking
object and
specifies the Type
property as a lower bound.
Properties
AbsTol
— Absolute tolerance used to determine bounds
0
(default) | nonnegative scalar
Absolute tolerance used to determine bounds as the signal approaches the reference signal, specified as a nonegative scalar.
The bounds on the reference signal are given by:
y_{u}
= (1 +
RelTol
)y_{r}
+ AbsTol
y_{l}
= (1 –
RelTol
)y_{r}
– AbsTol
where y_{r} is the value of the reference at a certain time, y_{u} and y_{l} are the upper and lower tolerance bounds corresponding to that time point.
Description
— Requirement description
''
(default) | character vector
Requirement description, specified as a character vector.
Example: 'Requirement on signal 1'
InterpolationTimes
— Time points to use when comparing reference and test point signals
"Reference
only"
(default) |
"Testpoint only"
| "Reference and Testpoint"
.
Time points to use when comparing reference and test point signals, specified as one of the following values:
"Reference only"
— Compare the signals at the time points of the reference signal only."Testpoint only"
— Compare the signals at the time points of the test point signal only."Reference and Testpoint"
— Compare the signals at the time points of both the reference and test point signals.
Linear interpolation is used to compare the signals at the same time points.
The sdo.requirements.SignalTracking
object stores the
value as a character vector.
Method
— Algorithm for evaluating the requirement
"SSE"
(default) |
"SAE"
| "Residuals"
Algorithm for evaluating the requirement when the
Type
property is
"=="
, specified as one of the
following values:
"SSE"
"SAE"
"Residuals"
When the requirement is evaluated using
evalRequirement
, the software
computes the error between the reference and test
point signals. This property specifies how the error
signal e(t)
=
y_{s}(t)
–
y_{r}(t) should be processed.
Name
— Requirement name
''
(default) | character vector
Requirement name, specified as a character vector.
Normalize
— Option to enable normalization
"on"
(default) |
"off"
Option to enable normalization, specified as
"on"
to enable normalization
and "off"
otherwise. The maximum
absolute value of the reference signal is used for
normalization.
The sdo.requirements.SignalTracking
object stores the
value as a character vector.
ReferenceSignal
— Reference signal to track
timeseries
object
Reference signal to track, specified as a
timeseries
object with real
finite data points.
RelTol
— Relative tolerance used to determine bounds
0
(default) | nonnegative scalar
Absolute tolerance used to determine bounds as the signal approaches the reference signal, specified as a nonegative scalar.
The bounds on the reference signal are given by:
y_{u}
= (1 +
RelTol
)y_{r}
+ AbsTol
y_{l}
= (1 –
RelTol
)y_{r}
– AbsTol
where y_{r} is the value of the reference at a certain time, y_{u} and y_{l} are the upper and lower tolerance bounds corresponding to that time point.
RobustCost
— Option to enable robust treatment of outliers
"off"
(default) | "on"
Option to enable robust treatment of outliers when
evaluating the requirement, specified as
"on"
to enable robust treatment
of outliers and "off"
otherwise.
When robust treatment of outliers is enabled and you
call evalRequirement
, the
software uses a Huber loss function to evaluate the
cost for the tracking error outliers. The tracking
error is calculated as e(t)=y_{ref}(t)-y_{test}(t). The software uses the error
statistics to identify the outliers.
The exact cost function used,
F(x),
depends on the requirement evaluation
Method
.
The sdo.requirements.SignalTracking
object stores the
value as a character vector.
Method Name | Cost Function for Nonoutliers | Cost Function for Outliers |
---|---|---|
"SSE" |
$$F(x)={\displaystyle \sum _{t\in NOL}e}(t)\times e(t)$$
NOL is the set of nonoutlier samples. |
$$F(x)={\displaystyle \sum _{t\in OL}w}\times |e(t)|$$
w is a linear weight. OL is the set of outlier samples. |
"SAE" |
$$F(x)={\displaystyle \sum _{t\in NOL}|}e(t)|$$
NOL is the set of nonoutlier samples. |
$$F(x)={\displaystyle \sum _{t\in OL}w}$$
w is a constant value. OL is the set of outlier samples. |
"Residuals" | The software does not remove the outliers. $$F(x)=\left[\begin{array}{c}e(0)\\ \vdots \\ e(N)\end{array}\right]$$ N is the number of samples. |
Type
— Tracking requirement type
"=="
(default) |
"<="
| ">="
Tracking requirement type, specified as one of the following values and stored as a character vector:
"=="
— Tracking objective."<="
— Upper bound">="
— Lower bound
Weights
— Weights to use when evaluating the tracking error
vector
Weights to use when evaluating the tracking error
between the reference and test point signals,
specified as a vector with the same number of
elements as the Time
property
of the timeseries
object in the
ReferenceSignal
property.
By default, the weights are all
1
.
Object Functions
copy | Copy design requirement |
get | Get design requirement property values |
set | Set design requirement property values |
evalRequirement | Evaluate design requirement |
Examples
Create Signal Tracking Requirements Object
Create a signal tracking object and specify a reference signal.
r = sdo.requirements.SignalTracking; r.ReferenceSignal = timeseries(1-exp(-(0:10)'));
Alternatively, you can specify the reference signal when you create the object
r = sdo.requirements.SignalTracking(...
ReferenceSignal=timeseries(1-exp(-(0:10)')));
Alternatives
Use getbounds
to get the
bounds specified in a Check Against Reference block.
Version History
Introduced in R2010b
See Also
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