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| R2011b Documentation → Model-Based Calibration Toolbox | |
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| R2011b Documentation → Model-Based Calibration Toolbox | |
Learn more about Model-Based Calibration Toolbox |
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| Contents | Index |
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This section takes you through the steps to create two separate point optimizations for use in combination in a drive cycle optimization. You create two optimizations so you can apply the peak pressure constraint only where it is relevant, at full load conditions.
Create a constrained point optimization to minimize BSFC (brake-specific fuel consumption) for each part load point.
Create a constrained point optimization to minimize BSFC for each full load point.
You use the results from both point optimizations as start points for a sum optimization.
To open CAGE and load the models for the optimization, follow these steps:
Enter cage to open the CAGE browser.
Load models to optimize. Select File > Import From Project. The CAGE Import Tool opens.
Click Import From Project File.
Locate the mbctraining folder and open the file DieselPointByPoint.mat.
Press Shift+click to select all models in the list, and click Import Selected Items. Then, click OK in the dialog box that appears next to import all the models. Then, close the Import Tool.
CAGE displays the variable connections for your imported point-by-point models.
To create the optimization, you perform the following tasks:
Select Tools > Create Optimization From Model.
The Create Optimization From Model wizard opens.
Select BSFC as the model to optimize, and click Next.
Leave all the defaults as shown to create a point optimization that:
Minimizes BSFC
Using the Model operating points as the Data source
With fixed variables SPEED and BTQ
Selects all other variables as free variables for CAGE to optimize
Adds the boundary model as a constraint
Click Finish to create the optimization.
CAGE displays your optimization. Rename your optimization to BSFC_PartLoad and continue to "Specify Number of Runs".
Observe the model operating points in the Optimization Point Set pane. Remove two of the runs. Later, your second optimization applies another constraint at the full load points.
Right-click the first run, where SPEED = 2200 and BTQ = 1263, and select Delete Runs.
Right-click the fourth run, where SPEED = 1600 and BTQ = 1550, and select Delete Runs.
Your optimization now has five runs. Continue to "Add a Constraint to the Optimization".
Add a constraint for air/fuel ratio before running the optimization. Follow these steps:
Right-click the Constraints pane, and select Add Constraint.
Select Constraint type Range.
Select Show models from the drop-down menu on the Bound Expression tab.
Select AFR in the model list.
Edit the constraint name to AFR.
Click the Lower Bound tab, and select the Vector option button. Ensure the Constraint description matches the following example, and click OK.
When the variable AFR_LowerBound appears in the Fixed Variables pane, copy and paste the following values into the AFR_LowerBound column.
| AFR_LowerBound |
|---|
| 27.5 |
| 30.0 |
| 0.0 |
| 20.0 |
| 22.5 |
Verify that your fixed variable values look like those in the following image.
You can now run your optimization:
Select Optimization > Run.
After CAGE calculates the optimization and displays the output, view the results.
Creating the full-load point optimization requires you to set up the optimization, define runs at full load, add the peak pressure constraint, and define required variables.
To set up the optimization, follow these steps:
Select Tools > Create Optimization From Model.
The Create Optimization From Model wizard opens.
Select BSFC as the model to optimize, and click Next.
Leave all the defaults, and click Finish to create the optimization.
Rename the new optimization to BSFC_FullLoad.
Inspect the model operating points in the Optimization Point Set pane. Because this optimization uses only the full-load points, right-click and delete all runs except where SPEED = 2200 and BTQ = 1263; SPEED = 1600, and BTQ = 1550. (Delete five runs total.)
Import the AFR constraint from the previous optimization.
Right-click the Constraints pane, and select Import Constraints.
Select the AFR constraint, and click OK.
You need some new variables to define a constraint and also to define some weights for the multiregion optimization. To save time you can import the variables and weights from the example project, rather than defining them manually, as follows:
Select File > Import From Project. The CAGE Import Tool opens.
Click Import From Project File.
Locate the mbctraining folder and open the file DieselPointByPoint.cag.
Select Dataset from the Type drop-down list.
Select DriveCycle10 in the list, and click Import Selected Items. In the following dialog box, you also import the variables you need for later steps:
BSFC_weights
BSNOX_DriveCycle10_weights
Click OK to import the data set and variables.
Select Variable from the Type drop-down list, select MaxPressure in the list, and click Import Selected Items. Click OK in the following dialog box to import the variable.
Close the Import Tool. You use all the items you imported in later steps.
Return to the BSFC_FullLoad optimization node, and add a peak pressure constraint, using the following steps:
Right-click the Constraints pane, and select Add Constraint.
Select the PEAKPRESS model.
Select the CAGE item option button, and then select Show variables from the drop-down menu.
Select MaxPressure in the variable list.
Rename the constraint to PEAKPRESS, and click OK.
Copy and paste the following values into the fixed variables columns for AFR_LowerBound and MaxPressure.
| AFR_LowerBound | MaxPressure |
|---|---|
| 25.5 | 15 |
| 20 | 18 |
When you finish defining all required variables, select Optimization > RunThen, continue next to "Create Multiregion Sum Optimization".
 | Point-by-Point Optimization Overview | Create Multiregion Sum Optimization |  |
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