Model Structures Defined by Initial Model

Ident can estimate models of any structure, supported by the System Identification Toolbox. Select Paramatric Models in the pop-up menu Estimate in the ident window, and chose By Initial Model in its Model structure pop-up menu.

Enter the name of any model structure in the Initial model: edit box of the Parametric Models dialog and then press the Estimate button. The method is a standard prediction error/maximum likelihood approach that iteratively searches for the minimum of a criterion. Options that govern this search are accessed via the Options button in the Iteration control... dialog.

The name of the model structure must be a variable in either the MATLAB workspace or on the Model board. In the latter case, you can just drag-and-drop the model icon over the Initial model: edit box.

Arbitrary model structures can be defined using several commands in the System Identification Toolbox:

IDPOLY
Creates input-output structures for single-output models.
IDSS
Creates linear state-space models with arbitrary, free parameters.
IDGREY
Creates completely arbitrary parametrizations of linear systems.
IDARX
Creates multi-variable ARX-structures.
SET
Modifies model structures.
See the manual for more information on these functions.

Help topics.

(file iduibn.htm)