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## Represent Binary Link Frame Tree

### Model Overview

In this example, you model the frame tree of a binary link. This tree contains three frames to which you later connect solid elements. You specify these frames using the Rigid Transform block.

You can promote subsystem reusability by parameterizing link dimensions in terms of MATLAB® variables. In this example, you initialize the variables in a subsystem mask. You can then specify their numerical values in the subsystem dialog box. Refer to the table for the dimensions needed to model the binary link frame tree.

DimensionMATLAB Variable
LengthL
Width W
ThicknessT

### Build Model

1. Drag these blocks into a new model.

BlockQuantityLibrary
Reference Frame1Frames and Transforms
Rigid Transform2Frames and Transforms
Solver Configuration1Simscape™ Utilities

2. Connect and name the blocks as shown in the figure.

 Note:   Pay close attention to Rigid Transform port orientation. Both base (B) port frames should connect to the Reference Frame port. This ensures the rigid transform applies to the Reference frame, and not the end frames.

3. In the Rigid Transform block dialog box, specify these parameters.

ParameterSetting
Translation > MethodSelect Standard Axis.
Translation > AxisSelect -X.
Translation > OffsetEnter L/2. Select units of cm.

4. In the Rigid Transform1 block dialog box, specify these parameters.

ParameterSetting
Translation > MethodSelect Cartesian.
Translation > OffsetEnter [L/2 0 3/2*T]. Select units of cm.

### Generate Binary Link Subsystem

To initialize the MATLAB dimension variables used to specify the frame transforms, convert the binary link block diagram into a subsystem and use the subsystem mask:

1. Select all the blocks excluding Solver Configuration.

2. Generate a new subsystem, e.g., by pressing Ctrl+G.

3. Select the Subsystem block and press Ctrl+M to create a subsystem mask.

4. In the Parameters & Dialog tab, add three text boxes to the Parameters folder and click OK.

PromptName
LengthL
WidthW
ThicknessT

5. In the subsystem dialog box, specify these parameters.

ParameterValue
Length30
Width2
Thickness0.8

### Visualize Model

Update the block diagram. You can do this in the Simulink® Editor menu bar, by selecting Simulation > Update Diagram. Then, in the Mechanics Explorer menu bar, select View > Show Frames. The visualization pane shows the binary link frame tree.

### Open Reference Model

To see a completed version of the frame tree model, at the MATLAB command prompt enter smdoc_binary_linke_frames.