How to load plugin from URDF in ignition ?

[doisyg]

Transitioning from Gazebo to Ignition, I am trying to use the spawner #60
I can successfully load an URDF which spawn a model in Ignition, but in don't understand how to load a plugin from the URDF.
More precisely I am trying to start the DiffDrive plugin, I put the following :

  <plugin
    filename="libignition-gazebo-diff-drive-system.so"
    name="ignition::gazebo::systems::DiffDrive">
    <left_joint>left_wheel_joint</left_joint>
    <right_joint>right_wheel_joint</right_joint>
    <wheel_separation>1.25</wheel_separation>
    <wheel_radius>0.3</wheel_radius>
    <!-- no odom_publisher_frequency defaults to 50 Hz -->
  </plugin>

below under robot tag but nothing seems to be loaded. However when using a sdf file and putting it under the model tag, it works properly. Maybe there is an equivalent to the urdf gazebo tag for ignition but I cannot find any example.

[diegoferigo]

Have you tried the following?

<robot name="model_name">
  <gazebo>
    <plugin filename="" ...>
      <!-- ... -->
    </plugin>
  </gazebo>
</robot>

The urdf file is converted by gazebo to sdf before being parsed by sdformat. You can test the conversion with ign sdf -p file.urdf.

[doisyg]

🤦‍♂️ 🤦‍♂️ 🤦‍♂️
Thanks, it works!
and ign sdf -p file.urdf is very useful for debugging

[diegoferigo]

For future reference, the URDF tutorial for Gazebo Classic seems still valid also for Ignition Gazebo. In particular, from the section <gazebo> element for the tag:

If a <gazebo> element is used without a reference="" property, it is assumed the <gazebo> element is for the whole robot model.

that can be applied also to model plugins.