User`s guide

4 Nonlinear Black-Box Model Identification
How to Estimate N
onlinear ARX Models in the GUI
You must have alr
eady imported your data into the System Identification
Tool GUI. For mor
e information about preparing your data, see Chapter 1,
“Data Processin
g”.
To estimate a no
nlinear ARX model in the System Identification Tool GUI:
1 In the System Id
entification Tool GU I, select Estima te > Nonlinear
models to open t
he Nonlinear Models d ialo g box. T he Model Type tab
is selected.
2 In the Model Structure list, select Nonlin ear ARX.
This action updates the options in the Nonlinear Models dialog box to
correspond to this model structure. For information about this model
structure, see “Definition of the Nonlinear ARX Model” on page 4-4.
3 In the Model n
ame field, edit the name of the m odel, or keep the default
name. The nam
e of the model should be unique to all nonlinear ARX
mod els in the
System Identification Tool GUI.
4 (Optional) If you want to try refining a previously estimated model, select
thenameofthismodelintheInitial model list.
Note The model structure and algorithm p roperties o f the initial model
populate the fields in the Nonlinear Models dialog box.
A model is available in the Initial model list unde r t he fo llowing
conditions:
• The model exists in the System Identification Tool GUI.
• The number of model inputs and o utputs matches the dimensions
of the Working Data (estimation data) you selected in the System
Identification Tool GUI.
5 Keep the d efault settings in the Nonlinear M odels dialog b ox that specify
the model structure and the algorithm, or modify the following settings:
4-10