What Are Model Arrays?
In many applications, it is useful to consider collections of multiple model objects. For example, you may want to consider a model with a parameter that varies across a range of values, such as
sys1 = tf(1, [1 1 1]); sys2 = tf(1, [1 1 2]); sys3 = tf(1, [1 1 3]);
and so on. Model arrays are a convenient way to store and analyze such a collection. Model arrays are collections of multiple linear models, stored as elements in a single MATLAB® array.
For all models collected in a single model array, the following attributes must be the same:
The number of inputs and outputs
The sample time
The time unit
Uses of Model Arrays
Uses of model arrays include:
Representing and analyzing sensitivity to parameter variations
Validating a controller design against several plant models
Representing linear models arising from the linearization of a nonlinear system at several operating points
Storing models obtained from several system identification experiments applied to one plant
Using model arrays, you can apply almost all of the basic model operations that
work on single model objects to entire sets of models at once. Functions operate on
arrays model by model, allowing you to manipulate an entire collection of models in
a vectorized fashion. You can also use analysis functions such as
to model arrays to analyze multiple models simultaneously. You can access the
individual models in the collection through MATLAB array indexing.
Visualizing Model Arrays
To visualize the concept of a model array, consider the set of five transfer function models shown below. In this example, each model has two inputs and two outputs. They differ by parameter variations in the individual model components.
Just as you might collect a set of two-by-two matrices in a multidimensional
array, you can collect this set of five transfer function models as a list in a
model array under one variable name, say,
sys. Each element of
the model array is a single model object.
Visualizing Selection of Models From Model Arrays
The following illustration shows how indexing selects models from a
one-dimensional model array. The illustration shows a 1-by-5 array
sysa of 2-input, 2-output transfer functions.
The following illustration shows selection of models from the two-dimensional