After Estimating Grey-Box Models

After estimating linear and nonlinear grey-box models, you can simulate the model output using the sim command. For more information, see Validating Models After Estimation.

The toolbox represents linear grey-box models using the idgrey model object. To convert grey-box models to state-space form, use the idss command, as described in Transforming Between Linear Model Representations. You must convert your model to an idss object to perform input-output concatenation or to use sample time conversion functions (c2d, d2c, d2d).

Note

Sample-time conversion functions require that you convert idgrey models with FunctionType ='cd' to idss models.

The toolbox represents nonlinear grey-box models as idnlgrey model objects. These model objects store the parameter values resulting from the estimation. You can access these parameters from the model objects to use these variables in computation in the MATLAB^® workspace.

Note

Linearization of nonlinear grey-box models is not supported.

You can import nonlinear and linear grey box models into a Simulink^® model using the System Identification Toolbox™ Block Library. For more information, see Simulate Identified Model in Simulink.