SolidWorks to URDF exports empty inertial matrices for some links only

asked 2019-02-06 18:44:41 -0600

antarctica gravatar image

Hi,

I'm trying to export a URDF for my 6 DoF base+arm and use it into Gazebo. I'm running Solidworks 2018 on Windows 10.

What I did:

  • Ensured that my parts are solid and have correct material properties
  • Specified origins and axes according to the standard
  • Separated links and joints, specifying their types
  • Exported the URDF

What happened:

  • The geometry exported perfectly, I can run the URDF into MoveIt and do some path planning on it
  • BUT the physical characteristics had some issues at export, and the inertia matrices of the two last links of the arm were empty (see URDF snippet). I suspect the exporter to be the issue, as the "mass and inertia properties" tool in SolidWorks outputs valid inertia values for all the parts. The result is very "jiggly" behavior in Gazebo as the inertia of the link is 0.

Has anyone run into this issue and knows how to solve it?

Thanks in advance :)

URDF snippet:

  <link
name="l_hand">
<inertial>
  <origin
    xyz="-0.0014356 0.07918 0.0014978"
    rpy="0 0 0" />
  <mass
    value="2.4998" />
  <inertia
    ixx="0"
    ixy="0"
    ixz="0"
    iyy="0"
    iyz="0"
    izz="0" />
</inertial>
<visual>
  <origin
    xyz="0 0 0"
    rpy="0 0 0" />
  <geometry>
    <mesh
      filename="package://lander_urdf/meshes/l_hand.STL" />
  </geometry>
  <material
    name="">
    <color
      rgba="0.79216 0.81961 0.93333 1" />
  </material>
</visual>
<collision>
  <origin
    xyz="0 0 0"
    rpy="0 0 0" />
  <geometry>
    <mesh
      filename="package://lander_urdf/meshes/l_hand.STL" />
  </geometry>
</collision>

</link>

-Ant

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