Learn more about Model-Based Calibration

How to Set Up a Two-Stage Model

The following steps are necessary to set up a two-stage model:

1. From the project node, create a new two-stage test plan. See Creating a New Test Plan.

2. From the test plan node, set up the inputs and models at the local and global stages. See Input Factor Setup, Local Model Setup and Global Model Setup.

3. At this point, you might want to design an experiment. See The Design Editor.

4. From the test plan node, load the data set you want to use. Select TestPlan > Select Data. See Loading Data from File.

   This opens the Data Wizard, where you can load a data set, match data signals to model variables and then set up the response model.

5. On completing the Data Wizard, the Data Editor opens. Here you can select data for modeling and match data to designs. See The Data Editor. Close the Data Editor and click Yes to accept the data for modeling.

   Note   On closing the Data Editor, the local and global models are calculated.

6. At the local node, you can view the fit of the local models to each test, and you can also view the global models at the response feature nodes.

7. You can create a boundary model at the test plan node. Boundary models describe the limits of the operating envelope and can be useful when you are creating and evaluating designs, optimization results and global models. It can be useful to create the boundary model before viewing global models, so you can see the model areas inside the boundary on plots. See Boundary Model Setup.

8. The two-stage model is not calculated until you use the Select button (from the local node, in the Response Features pane) and choose a model as best (even if it is the only one so far), unless you go straight to MLE. See below.

   See Selecting Models.

   Note   At this point, the two-stage model is calculated, and the icon changes at the local node to reflect this. See Icons: Curves, Worlds, and Houses.

9. You are prompted to calculate the maximum likelihood estimate (MLE) at this point. You can do this now, or later by selecting Model > Calculate MLE. See MLE for a detailed explanation.

   Note   If there are exactly enough response features for the model, you can go straight to MLE calculation without going through the Select process. The MLE toolbar button and the Model > Calculate MLE menu item are both active in this case. If you add new response features, you cannot calculate MLE until you go through model selection to choose the response features to use.

See Two-Stage Models for Engines for a detailed explanation of two-stage models.

Double-click the Model blocks of the block diagram or select the TestPlan > Set Up Model menu item. The toolbox supports a wide range of models.

For model descriptions, see Global Model Setup and Local Model Setup.

Once you have built a single model, you should create more models for comparison, to search for the best fit. You can follow the guidelines in the next section, Creating Alternative Models to Compare.

How to Set Up a One-Stage Model

How to Set Up a Point-by-Point Model

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