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Export CAD Robot Arm

CAD Robot Arm Files

The following example is based on a more complex CAD assembly, a robot arm. It includes multiple parts, two closed loops, multiple constraints, and a subassembly. Look for the 11 CAD files of this case study in the SimMechanics™ Link examples folder.

File NameCAD File Type
robot.ASSEMBLYFILETYPEAssembly
grip.ASSEMBLYFILETYPESubassembly (flexible)
base.PARTFILETYPE
forearm.PARTFILETYPE
upperarm.PARTFILETYPE
wrist.PARTFILETYPE
Parts (main assembly)
fingertips.PARTFILETYPE (twice)
firstfingerlink.PARTFILETYPE
firstfingerlinkL.PARTFILETYPE
metacarpal.PARTFILETYPE
secondfingerlink.PARTFILETYPE (twice)
Parts (subassembly)

CAD Robot Arm Properties

Open the assembly file for the whole robot.

Robot Arm Assembly in a CAD Platform

In the assembly tree to the left of the window, examine the CAD hierarchy:

  • Five of the part files are grouped into the subassembly grip. The subassembly uses two instances each of fingertips and secondfingerlink.

  • The subassembly has its own group of 18 constraints, MateGroup1.

    Two constraints, Angle1 and Angle2, are not active. If they were, they would lock the grip fingers into the open position. Here, each grip finger can move separately.

  • The other four part files are separate and grouped into the main assembly.

  • The main assembly has its own MateGroup1, consisting of seven constraints.

The whole assembly has eight DoFs. The grip subassembly alone contains two, allowing each finger to open and close separately. The main assembly has six DoFs:

  • The upper arm can move relative to the base by pitching, yawing, and rolling (three DoFs).

  • The forearm can yaw relative to the upper arm (one DoF).

  • The wrist can pitch relative to the forearm (one DoF).

  • The grip can rotate about its symmetry axis (one DoF).

Export Robot Arm Assembly

Apply any changes you want to the assembly configuration or settings. If you change the assembly or any subassemblies, you need to rebuild the assembly before exporting it to XML.

Using the SimMechanics Link interface to your CAD platform, export the assembly into Physical Modeling XML. The XML file robot.xml appears in your working CAD folder.

Import Model

Once you have exported the CAD assembly, you can generate the corresponding SimMechanics model. Using the mech_import command, you import the Physical Modeling XML file that SimMechanics Link generated during export, and let SimMechanics automatically generate the model for you. Then, review the model and make any required changes to the model. For a step-by-step description of the CAD Import procedure, see Import Robot Arm Model.

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