Setting Up a Tradeoff Calibration

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Overview of Setting Up a Tradeoff Adding a Tradeoff Adding Tables to a Tradeoff Displaying Models in Tradeoff

Overview of Setting Up a Tradeoff

A tradeoff calibration is the process of filling lookup tables by balancing different objectives.

Typically there are many different and conflicting objectives. For example, a calibrator might want to maximize torque while restricting nitrogen oxides (NOX) emissions. It is not possible to achieve maximum torque and minimum NOX together, but it is possible to trade off a slight reduction in torque for a reduction of NOX emissions. Thus, a calibrator chooses the values of the input variables that produce this slight loss in torque instead of the values that produce the maximum value of torque.

A tradeoff also refers to the object that contains the models and tables. Thus, a simple tradeoff can involve balancing the torque output while restricting NOX emissions.

After you set up your variable items and models, you can follow the procedure below to set up your tradeoff calibration:

1. Add a tradeoff. This is described in the next section, Adding a Tradeoff.

2. Add tables to the tradeoff. This is described in Adding Tables to a Tradeoff.

3. Display the models. This is described in Displaying Models in Tradeoff.

This section describes steps 1, 2, and 3 in turn.

When you finish these steps, you are ready to calibrate the tables.

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Adding a Tradeoff

To add a tradeoff to your session, select File > New > Tradeoff. This automatically switches you to the Tradeoff view and adds an empty tradeoff to your session.

An incomplete tradeoff is a tradeoff that does not contain any tables. If a tradeoff is incomplete, it is displayed as in the tree display. If a tradeoff is complete, it is displayed as in the tree display.

After you add a tradeoff you must add tables to your tradeoff.

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Adding Tables to a Tradeoff

1. Add a table by selecting Tradeoff -> Add New Table or click in the toolbar. You can also add existing tables from your CAGE session; see Adding Existing Tables.

   Note that you must select the top tradeoff node in the tree display to use the Tradeoff menu. This is automatically selected if your tradeoff has no tables yet (it is the only node). You must also add at least three variables (in the variable dictionary) to your project before you can add a table, because CAGE needs a variable to fill the table and two more variables to define each of the two normalizers.

   A dialog box opens.

   

2. Enter the name for the table.

   If your tradeoff already contains one or more tables, when you add additional tables they must be the same size and have the same inputs (and therefore have the same normalizers). So if your tradeoff has existing tables, you can only enter the new table name and the initial value.

   For the first table in a tradeoff, you must set the normalizer inputs and sizes:

   1. Edit the names for the X and Y normalizer inputs (the first two variables in the current variable dictionary are automatically selected here).

   2. Enter sizes for each of the normalizers (Y input = rows, X input = columns)

3. Enter an initial value to fill the table cells, or leave this at zero.

4. Click Select to choose a filling item for a table. A dialog opens where you can select from the models and variables in your session.

   

   1. Depending on what kind of input you want, click the radio buttons to display models or variables or both. You can choose to also show items that are filling another table by clearing the check box.

   2. Select the filling item for the table and click OK.

5. Click OK to dismiss the Table Setup dialog and create the new table.

   CAGE adds a table node to the tradeoff tree. Note you can still change the input for the table as follows. Double-click the new table in the list under Tables In Tradeoff, or click to select the table (it is selected automatically if it is the only table in the tradeoff) and then click Change Filling Item ( ) in the toolbar. This is also in the Tradeoff menu and the right-click context menu.

   The Select Filling Item dialog appears where you can select inputs to fill the table, as described above.

6. Repeat this procedure for each new table you want to add. Each additional table in the tradeoff must have the same normalizers as the first table, so you do not have to select normalizer inputs and sizes repeatedly. For each new table you only have to enter the name and initial value.

Adding Existing Tables

1. Add a table by selecting Tradeoff > Add Existing Tables or click in the toolbar.

   A dialog appears where you can select from a list of tables in the current session.

2. Select a table and click OK. It may be helpful to first select the check box to only show suitable tables that can be added to the tradeoff.

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Displaying Models in Tradeoff

To display models when viewing tables in the tradeoff display,

1. Highlight the tradeoff node in the tree.

2. From the Available Models list, select the one you want to display.

   Models that are filling a table are automatically displayed.

3. Click Add Model to Display List in the toolbar or in the Additional Display Models pane to move the selected model into the Display Models pane. To quickly add all available models to the display list, click the display button repeatedly and each successive model will be added.

4. Repeat steps 2 and 3 to add all the models you want to the display list.

   

Removing a Model

1. In the Display Models list, select the model that you want to remove.

2. Click in the toolbar, or in the Display Models pane, to move the selected model into the Available Models pane.

3. Repeat until you have cleared all the appropriate models.

Once you have displayed all the models that you want to work with, you are ready to calibrate your tables.

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Performing a Tradeoff Calibration

Calibrating Tables in a Tradeoff Calibration

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