Construct Models

MBS models can be created interactively in MotionView using its easy to use interface.

Add an Entity

To add an entity:
  1. Click on the icon in the Ribbon to bring up the Add “Entity” dialog.
    Attention: Points, Vectors, Joints, and Bushings are added using the guide bar in the modeling window (not the Add "Entity" dialog).
  2. Enter a Label and Variable for the entity.
  3. Click OK to add the entity and close the dialog.
    Tip: Click Apply to add the entity while retaining the dialog to add additional entities.
When the entity is added, the last added entity gets selected and its panel is displayed in the panel area. The entity is now available for editing.
Note: Certain entities like Point, Body, Graphics, Joints, Bushings, SpringDamper, Forces etc. can be added as pair. A pair can be made symmetric in the Global XZ plane

It is recommended to provide a meaningful Variable name (varname) to entities. Entities are identified and referenced through their variable names.

Edit an Entity

An entity can be selected by clicking on the entity in the browser or by clicking on the entity graphics (if available) in the modeling window.

Attention: Points, Vectors, Joints, and Bushings are edited using the property editor in the browser (not the panel).
The panel for an entity shows its properties, reference to other entities and are arranged in horizontal tabs. Pair entities will have Left and Right vertical tabs.

Figure 1.
A property could be any one of the following:
  • Real, Integer, String data
  • File reference
  • Drop-down option
  • Entity reference
A property can be parametrically linked to a property of another entity.

Figure 2.
The Expression Builder can be used to build complex expressions and access entity properties.

Figure 3.
An entity reference in the panel is indicated by a yellow colored collector. Clicking on the collector makes it active indicated by a cyan border. When picking mode is active on a collector, the entity selector gets deactivated.

Figure 4.
When the collector is active, the reference can be resolved through:
  1. Picking the entity in the graphics area, if the entity has a graphical representation.


  2. Select dialog by clicking again (double-click) on the collector.

Figure 5.

Mouse and Keyboard Controls

Use the following mouse and keyboard controls to manipulate the view of the model in the modeling window.
Press To do this
Ctrl+Left mouse Rotate the model.
Ctrl+Right mouse Pan the model.
Ctrl+Scroll wheel Zoom in/out.
'F’ key Fit the model to the window.

Creating a multibody model consists of creating entities such as bodies, points, graphics, joints, force elements and outputs. A CAD geometry can also be used as an input to create bodies and graphics.

Use CAD Geometry

MotionView supports reading several variety of CAD formats. CAD components can be imported to create bodies and associated graphics.

Interact with CAD geometry

MotionView can recognize features in the CADGraphics that may be used to create points and curves needed as reference for other entities. This feature needs to be turned on (off by default) from File > Preferences click the Preferences button to display the Options dialog and select Build Model.

With this feature on, geometrical objects can be used to define MotionView entities. For example, while picking into a Point collector, an arc center can be located to automatically create a point at that location.

Figure 6.
Similarly, an edge or an axis can be used to automatically create vector entity.

Figure 7.

To learn how to save and open models see the Opening and Saving a Model File topic.

Construct a Model

MBD models can be created using one or more of the following techniques:

  1. Construct a model through the user interface. Entities can be added and deleted and their values set within the MotionView interface. These models can be saved directly from MotionView to an MDL file.
  2. Edit the MDL files directly. After you construct an MDL model, you can load it into MotionView at a later time for simulation use.
  3. Assemble a model from the MDL library. A vehicle suspension and dynamics library is installed with MotionView by default which contains simple MDL modules. The library can be expanded or recreated for other mechanism types.

Please note the following about MDL and the MotionView interface:

  • A data field can be defined as a parametric data expression. Select any data field and click at the top of the panel.
  • To create parametric or non-parametric text that is to be exported to the solver input file and is not defined using the MDL language, use the Templex template.
  • The full model tree can be viewed by selecting Browsers > MotionView > Project from the View menu.
  • To access all model data in one dialog, select Data Summary from the top-right of select panels.
  • Select Check Model from the Tools menu before starting a simulation. This ensures that dependencies have been resolved and sets the IDs of the solver input file items.