Model Browser User's Guide

Setting Up the Local Model

Setting up the local model requires that you specify the model's inputs and type.

Specifying the Local Model Input

The model you are building is intended to predict the torque generated by an engine as a function of spark angle at a specified operating point defined by the engine's speed, air/fuel ratio, and load. The input to the local model is therefore the spark angle.

To specify spark angle as the input:

1. Double-click the Local Inputs icon on the model diagram to specify the local model input.

1. The Local Input Factor Setup dialog box appears.

   

   1. Set Symbol to S.
   2. Set Signal to spark. This is optional and matches the raw data.

2. Click OK to dismiss the dialog box.

Notice that the new name of the local model input now appears on the two-stage model diagram.

Specifying the Local Model Type

The type of a local model is the shape of curve used to fit the test data, for example, quadratic, cubic, or polyspline curves. In this example, you use polyspline curves to fit the test data. A spline is a curve made up of pieces of polynomial, joined smoothly together. The points of the joins are called knots. In this case, there is only one knot. These polynomial spline curves are very useful for torque/spark models, where different curvature is required above and below the maximum.

To specify polyspline as the model type:

1. Double-click the local model icon in the model diagram.

1. The Local Model Setup dialog box appears.

   

   1. Select Polynomial Spline from the Local Model Class.
   2. Set Spline Order to 2 below and 2 above knot.

2. Click OK to dismiss the dialog box.

Notice that the new name of the local model class, PS (for polyspline) 2,2 (for spline order above and below knot) now appears on the two-stage model diagram.

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Setting Up the Model

Setting Up the Global Model