<joint> <axis> not working correctly in combination with <include> inside <model> (nested model) in sdf >= 1.5 unless old behaviour (sdf <= 1.4) is restored via <use_parent_model_frame>

[osrf-migration]

Original report (archived issue) by Andreas Bihlmaier (Bitbucket: andreasBihlmaier).

The original report had attachments: broken_joint_axis_include_demo.tgz

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Hi everyone,

I found an issue regarding the "new" (SDF >= 1.5) behavior of in combination with :
The axis of all models that are d with a are wrong. To be more precise, it appears that they do not take the into account and thus turn up wrong with respect to all other coordinate systems in the d model.
The issue is easily reproducible in Gazebo 7 and 8. A minimal example follows (and is attached) together with three screenshots that show the issue using the "Demo Joint Types" model from the online repository.
As there is simply a coordinate transform missing somewhere, I'd estimate someone more familiar with this part of the Gazebo code base, will be able to quickly fix it. I would highly appreciate it.

#!xml

<?xml version="1.0" ?>
<sdf version="1.6">
  <model name="broken_joint_axis_include_demo">

    <include>
      <uri>model://demo_joint_types</uri>
      <name>model1</name>
    </include>

    <include>
      <uri>model://demo_joint_types</uri>
      <name>model2</name>
      <pose>
        2 0 0
        0 0 1.57079 
      </pose>
    </include>

    <joint name="rd_drive_torque_to_beer_joint" type="fixed">
      <parent>model1::heavy_base</parent>
      <child>model2::heavy_base</child>
    </joint>
    
  </model>
</sdf>

The combined model:

Correct :

Wrong in d model:

Note: Everything works if all joints in the d model use <use_parent_model_frame>1</use_parent_model_frame>, but then we are back at the non-intuitive way is defined (to model instead of child frame).

[osrf-migration]

Original comment by Andreas Bihlmaier (Bitbucket: andreasBihlmaier).

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• Edited issue description

[osrf-migration]

Original comment by Andreas Bihlmaier (Bitbucket: andreasBihlmaier).

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• Edited issue description

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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It looks like your example is using nested models. I think the joint axis is being interpreted correctly if a model is <include>d into a world. If so, let's update the title to indicate that this bug refers specifically to nested models, since that will help us focus our search for a fix.

[osrf-migration]

Original comment by Andreas Bihlmaier (Bitbucket: andreasBihlmaier).

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• changed title from " not working correctly in combination with in sdf >= 1.5 unless old behaviour (sdf <= 1.4) is restored via <use_parent_model_frame>" to " not working correctly in combination with inside (nested model) in sdf >= 1.5 unless old behaviour (sdf <= 1.4) is restored via <use_parent_model_frame>"

[osrf-migration]

Original comment by Andreas Bihlmaier (Bitbucket: andreasBihlmaier).

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@scpeters Yes, this issue only pertains to inside a tag. I updated the title accordingly.

[osrf-migration]

Original comment by Guilherme Carvalho (Bitbucket: guilhermepscarvalho).

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ping!

Was this solved in Gazebo 9?

[osrf-migration]

Original comment by Andreas Bihlmaier (Bitbucket: andreasBihlmaier).

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Running gazebo9 9.4.1-1~bionic I cannot use the "Demo Joint Types" model anymore:

[osrf-migration]

Original comment by Andreas Bihlmaier (Bitbucket: andreasBihlmaier).

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Issue still persists:

#!xml

<?xml version="1.0"?>

<model>
  <name>Broken Joint Axis Include Demo 2</name>
  <version>1.0</version>
  <sdf>model.sdf</sdf>

  <author>
    <name>Andreas Bihlmaier</name>
    <email>bihlmaier@robodev.eu</email>
  </author>

  <description>
    Demonstrates how joint axis is broken when using include unless use_parent_model_frame is used.
    Uses two instances of "Demo Joint Friction" from Gazebo model repository.
		Btw. "Demo Joint Types" is broken!
  </description>
</model>

#!xml

<?xml version="1.0" ?>
<sdf version="1.6">
  <model name="broken_joint_axis_include_demo2">

    <include>
      <uri>model://demo_joint_friction</uri>
      <name>model1</name>
    </include>

    <include>
      <uri>model://demo_joint_friction</uri>
      <name>model2</name>
      <pose>
        2 0 0
        0 0 1.57079 
      </pose>
    </include>

    <joint name="some_fixed_joint" type="fixed">
      <parent>model1::link_base</parent>
      <child>model2::link_base</child>
    </joint>
    
  </model>
</sdf>

[osrf-migration]

Original comment by Shane Loretz (Bitbucket: Shane Loretz, GitHub: sloretz).

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Running gazebo9 9.4.1-1~bionic I cannot use the "Demo Joint Types" model anymore:

Gazebo 9 is unable to load Demo joint types because at some point the code handling revolute2 joints got broken. See issue #2239.