Troubleshoot CAD Export Issues

During CAD export, Simscape™ Multibody™ Link can encounter CAD translation issues that arise from unsupported CAD elements. The following issues are known.

Unsupported Constraints

If a CAD assembly contains one or more unsupported constraints or mates, the Simscape Multibody Link utility issues a warning message and creates a log file in the folder of the XML multibody description file. The warning message identifies the name of the log file; the log file identifies the unsupported CAD constraints. In the event a constraint warning occurs, review the log file and consider replacing the unsupported constraints or mates with supported equivalents.

The constraint warning does not stop the creation of the XML multibody description file. You can import the XML file into a new Simscape Multibody model, but the model does not accurately represent the original CAD assembly. During import, constraint warnings appear at the MATLAB® command line.

For a list of supported constraints, see Constraints and Joints.

Correct Constraint Issue

When you import a CAD assembly that contains an unsupported constraint, Simscape Multibody replaces the constraint with a rigid connection. The connection provides zero degrees of freedom between the connecting rigid body frames. To restore the original degrees of freedom between the rigid bodies frames, you must:

  • In the CAD platform, replace each unsupported constraint with a supported equivalent. When you are finished, export the CAD assembly once again.

  • In the imported Simscape Multibody model, manually replace each artificially introduced rigid connection with the appropriate joint or constraint block.


Replacing unsupported constraints with supported equivalents works in a limited number of cases. In certain cases, no adequate equivalent constraint or joint block exists.

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