MV-7031: Tracked Vehicle Modeling

In this tutorial, you will learn how to use MotionView to build a tracked vehicle and MotionSolve to simulate the vehicle passing over a slope.

This tutorial will take approximately 30 minutes to build and 30 minutes to solve.

Open and Review the Model

From the mbd_modeling\interactive\track folder, copy the files Track_Start.mdl and soil_input.dat to your <working directory>.
  1. Start a new MotionView session.
  2. Click the (Open Model) icon to open the Track_Start.mdl model file.
  3. Review the model.
    1. The model is in the mm, Kg, N, sec unit system.
    2. The model has two systems: Body and Suspension.
    3. The Body system contains the Vehicle body (Frame) and Engine fixed to each other.
    4. The Suspension system has three trailing arms connected with a torsional spring damper.


    Figure 1.

Create Rolling Systems

  1. From the Model menu, select Track builder > Create rolling system.


    Figure 2.
  2. Select the Symmetric pair check box to create both the left and right rolling system together.
    Note: The symmetry needs to be about the x-z plane.
  3. Clear the Use CAD/H3D graphics for rolling element check box.
  4. Clear the Use mass, inertia rolling element check box.
  5. Use the table below to create a Sprocket type rolling system.
    Rolling System Varname Rolling System Label X Y Z Radius Thickness Number of Teeth Attach to Single/Left Attach to Right
    Sysr_spr Sprocket 0 -500 400 200 100 16 Frame Frame


    Figure 3.
  6. Click Apply to apply the sprockets to the body Frame.
    Wait until the sprockets have been fully generated before creating the next rolling system.
  7. Use the table below to create multiple Wheel type rolling systems.
    Tip: Use the Apply button to keep the dialog open when creating multiple rolling systems.
    Rolling System Varname Rolling System Label X Y Z Radius Thickness Attach to Single/Left Attach to Right
    Sysr_frntw FrontWhl 300 -500 0 200 100 Front Arm-Left Front Arm-Right
    Sysr_midw MidWhl 800 -500 0 200 100 Mid Arm-Left Mid Arm-Right
    Sysr_rearw RearWhl 1300 -500 0 200 100 Rear Arm-Left Rear Arm-Right


    Figure 4.
  8. The model with all of the defined rolling systems is shown below:


    Figure 5.

Create Track Systems

  1. From the Model menu, select Track builder > Create track.


    Figure 6.
  2. Enter 4 in the Total number of Entities field to wrap on the four rolling systems that were created.
    This will update the entity selector table to enter four values.
  3. Set the Wrap varname as sysw_trklh and the Wrap label as Track LH.
  4. Verify that the Track/Chain option is selected.
  5. Select Systems to wrap in the order shown below and set the Wraptype as Inside for each system.
    1. Sprocket LH
    2. RearWhl LH
    3. MidWhl LH
    4. FrontWhl LH
    Note: The order of the selected wheels should represent the way the chain is wrapping the sprocket and wheels in a clockwise direction.
  6. Enter Link length as 85.84, Link thickness as 40.0, and Link width as 150.
  7. After selection, the preview window will be updated with wrapping.
  8. Once the basic properties are defined, the dialog (see: Minimum number of links) will suggest the minimum number of links required to wrap the system. In this case, it will be 49. Enter 49 for the Number of links/segments.
    The preview window will now show a closed track.
  9. Clear the Use CAD/H3d graphics for links check box.
  10. Clear the User mass, Inertia for links check box.
  11. Select the Soil Interaction option and set the Interaction type as Soft Soil.
  12. Select the Soil terrain file soil_input.dat from the <working directory>.
  13. Set the Link DOF to 1-Rotation free.
    The links will be connected using revolute joints and will only have one relative rotational DOF between them.
  14. Activate the Create Terrain Graphics option.
  15. Set a new Terrain graphics file as TGra.x_t file in the <working directory>.
    This file will be created based on the profile defined in the Soil Terrain File.
  16. The contact setting will be filled automatically based on the model units. Use the default setting for this model.
  17. Click Apply to create the track for the left side.


    Figure 7.
    The Track with Terrain Graphics is shown below:


    Figure 8.
  18. Using the same properties, create the track for right side with varname as sysw_trkrh and label as Track RH. Define the Systems to wrap in the order shown below and set the Wraptype as Inside for each system.
    1. Sprocket RH
    2. RearWhl RH
    3. MidWhl RH
    4. FrontWhl RH
  19. Clear the Create Terrain Graphics check box, since the graphics are already created and the same soil terrain is being used for both the left and right in this tutorial.
  20. Click OK to accept the track and close the window.
  21. The completed model is shown below.


    Figure 9.

Verify Soil Properties

The soil properties and link geometries are created by default and require user modification based on the vehicle specification.
  1. From the Model menu, select Track builder > Updated link geometry to view the parameters.


    Figure 10.
  2. The Update Link Geometry dialog contains some basic properties and link geometric properties. Review the data and click Cancel to close the dialog.


    Figure 11.
  3. From the Model menu, select Track builder > Update soft soil to view the parameters.


    Figure 12.
  4. The Update soft soil properties dialog contains the details of terrain and soil properties. Review the data and click Cancel to close the dialog.


    Figure 13.
    Note: To learn more about the link and soft soil properties, please see Track Model.

Simulation and Post-Processing

  1. There are two motions, Motion 0 and Motion 1 in the model.
  2. Update the joint of Motion 0 to Sprocket LH Joint Rev by selecting the revolute joint between Sprocket LH and Frame.
  3. Update the joint of Motion 1 to Sprocket RH Joint Rev by selecting the revolute joint between Sprocket RH and Frame.
  4. In the Run panel, simulate the model for 10 Sec.
  5. Click the Animate button to load your results in a HyperView window.
  6. From the Animation toolbar, click the (Start/Pause Animation) button to animate the model.
  7. Visualize the animation.


    Figure 14.
  8. From the Page Controls toolbar, click the (Add Page) icon.
  9. In the Select Application drop-down menu, change the client to HyperGraph 2D.
  10. From the Build Plots panel, click to load the .abf file from the MotionSolve run.
  11. Plot the Sinkage of link 0 under Y type - REQSUB.


    Figure 15.


    Figure 16.