Create a Tradeoff from an Optimization

Typically, there are many different and conflicting calibration 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 tradeoff a slight reduction in torque for a reduction of NOX emissions. A calibrator chooses the values of the input variables that produce the slight torque loss over the values that produce the maximum torque.

Use MBC Optimization app with statistical models created in MBC Model Fitting app to balance competing objectives and fill lookup tables that control engine functions. After you import your models, you can create a tradeoff. The easiest way to automate trading off competing objectives is to create a tradeoff from an optimization. Follow this workflow.

StepDescription
1

Import Models

Use the MBC Model Fitting app to import models to CAGE.

Icon with text ‘Generate Calibration’ and tooltip reading ‘Generate calibrations with models.

2

Create Lookup Tables and Tradeoff from Model

Click Lookup Tables and Tradeoff to use the Create Lookup Tables from Model wizard to create the tables and tradeoffs.

Interface titled ‘Lookup Tables and Tradeoff’ showing a grid of plots, a color-coded table, and a 3D surface chart.

3

Create Optimization

Click Optimization to use the Optimization Quick Start Tool to create the optimization.

Optimization interface showing tables, contour plot, and performance graph with a hand cursor selecting a point.

4

Run Optimization

On the Common Tasks pane, click Run to run the optimization.

Common Tasks menu showing options: Add Constraint, Set Up, and Run with a cursor on Run.

5

Fill Lookup Tables

On the Common Tasks pane, click Fill Tables to fill the tables with the optimization results.

Common Tasks menu showing options: Fill Tables, Tradeoff, and Create Sum Optimization with a cursor on Fill Tables.

6

Analyze Results

On the Processes pane, select Tradeoffs to analyze the tradeoff tables.

Processes panel showing icons for Feature Filling and Tradeoffs, with cursor on Tradeoffs.

Import Models

Use the MBC Model Fitting app to import models to CAGE. For example, import the duel CAM gasoline engine with spark models.

  1. In the command window, to open the MBC Model Fitting app, enter mbcmodel.

  2. In the case studies pane, select Duel CAM gasoline engine with spark optimized during testing.

    Case Studies pane in Model browser.

  3. On the home page of the MBC Model Fitting app, to open CAGE, select Generate Calibration.

    Generate Calibration icon in MBC Model Fitting app.

  4. In the Import Models dialog box, to import the models, select OK. CAGE creates models.

    Import Models dialog box.

Create Lookup Tables and Tradeoff from Model

In CAGE, use the Create Lookup Tables from Model wizard to create the tables and tradeoff. For example, create tables and a tradeoff for the duel CAM gasoline engine with spark models.

  1. After you have imported the models for the dual CAM gasoline engine, on the CAGE homepage, select Lookup Tables and Tradeoff.

    Interface labeled ‘Lookup Tables and Tradeoff’ showing a color-coded table, 3D surface plot, and multiple parameter graphs.

  2. In the Create Lookup Tables from Model wizard:

    1. Base the new tables on the Torque model. Click Next.

      Create Lookup Tables from Model dialog box with the Torque model selected.

    2. Set up the normalizers for the tables. Select Next to accept the defaults.

      Dialog titled ‘Create Lookup Tables from Model’ showing inputs for LOAD and Speed with normalizer options, table rows and columns set to 10, and two tables listing input values and table outputs.

    3. Click Finish to create the tables. By default, the Optimization/Tradeoff fill process is on.

      Create Lookup Tables from Model dialog box displaying the Lookup Tables page.

  3. In the CAGE browser Tradeoffs view, confirm the tables in the tradeoff.

    CAGE browser displaying the Tradeoffs pane with the Torque_Tradeoff selected.

Create Optimization

In CAGE, use the Optimization Quick Start Tool to create the optimization. For example, create an optimization for the duel CAM gasoline engine with spark.

  1. After you have created the tables and tradeoffs for the duel CAM gasoline engine, on the CAGE homepage, select Optimization.

    Optimization window showing tables, contour plot, and performance graph with a hand cursor selecting a point.

  2. In the Optimization Quick Start dialog box:

    1. On the Objectives page:

      • Set Optimization type to Single-objective: optimize a single objective.

      • Set Model to Torque.

      • Set Goal to maximize.

      • Set Variable to ECP, ICP, and LOAD.

      Optimization Quick Start dialog box displaying the Objectives page.

    2. On the Constraints page:

      • Select Add a model boundary constraint.

      Optimization Quick Start dialog box displaying the Constraints page.

    3. On the Operating Points page:

      • Set Operating points to Breakpoints and Torque_Table(LOAD,Speed).

      • Set Optimize operating points to Point: optimize each operating point separately.

      Optimization Quick Start dialog box displaying the Operating Points page.

    4. In the CAGE browser Optimization view, confirm the objectives and constraints.

      Optimization view in the CAGE browser displaying the objectives and constraints.

Run Optimization

In CAGE, on the Common Tasks pane, click Run to run the optimization. For example, run the optimization for the duel CAM gasoline engine with spark.

  1. After you have set up the optimization for the duel CAM gasoline engine models, on the Common Tasks pane, click Run. View the progress.

    Optimization Progress dialog box for the Torque_Optimization.

  2. After the optimization completes, view the results.

    CAGE browser displaying the optimization results.

Fill Lookup Tables

In CAGE, on the Common Tasks pane, click Fill Lookup Tables to fill the tables with the optimization results. For example, fill the tables with the duel CAM gasoline engine with spark optimization results.

  1. After you have run the optimization for the duel CAM gasoline engine models, on the Common Tasks pane, click Fill Lookup Tables. In the Lookup Table Filling from Optimization Results wizard, click Next.

  2. In the Lookup Table Filling from Optimization Results wizard, select the optimization results that you want to fill each table with. Click Next to accept the defaults.

    Lookup Table Filling from Optimization Results Wizard dialog box displaying the Optimal Result Selection.

  3. In the Lookup Table Filling from Optimization Results wizard, select the lookup table filling algorithm. Click Finish to accept the defaults.

    Lookup Table Filling from Optimization Results Wizard dialog box displaying the Fill Algorithm.

Analyze Results

If the tradeoff view is not opened, on the Processes pane, select Tradeoffs to analyze the tradeoff tables.

Processes panel with icons for Feature Filling and Tradeoffs; cursor points to Tradeoffs.

In the tradeoff view, you can:

  • Select an optimization for comparison with the current table values.

    OptionGoal
    Open

    Open the optimization results

    Run

    Set the initial values to the table values and rerun the optimization

    Initialize

    Set all tradeoff points to the optimization solution

  • Double-click the table lines to set the tables and tradeoff.

    • Orange line updates tables to the tradeoff values.

    • Blue line sets the tradeoff value to the optimization solution at that operating point.

    • Purple line sets the tradeoff value to the table value at that operating point.

  • View the tradeoff points on the surface table view. Select the white dots to change the table operating point. Right-click the table surface to edit or print to a figure.

For example, after you have run the optimization for the duel CAM gasoline engine models, on the Processes pane, select Tradeoffs to analyze the tradeoff tables.

CAGE browser displaying the Tradeoff results.

See Also

Topics