[gazebo9] URDF to SDF only loads 4 joints

[ahoarau]

When I try to convert the generated icub.urdf to sdf :

gz sdf -p  icub.urdf

It only converts 4 joints :

gz sdf -p icub.urdf | grep joint

    <collision name='base_link_fixed_joint_lump__root_link_collision'>
    <visual name='base_link_fixed_joint_lump__root_link_visual'>
    <joint name='l_hip_pitch' type='revolute'>
    </joint>
    <joint name='l_hip_roll' type='revolute'>
    </joint>
    <joint name='r_hip_pitch' type='revolute'>
    </joint>
    <joint name='r_hip_roll' type='revolute'>
    </joint>

[traversaro]

Which model are you trying to convert?

Issues that could be related:

• https://bitbucket.org/osrf/sdformat/issues/105/urdf-parser-fails-if-two-consecutive-fixed

[ahoarau]

This one https://github.com/robotology/icub-model-generator/blob/master/dh/generated/urdf/icubGazeboSim/icub.urdf

Most probably related to this indeed.

[traversaro]

The reason is actually described in robotology/icub-models#112 (comment) . TL;DR: Due to problems in the original data used to create the URDF for v1 parts of iCub, torso_1, torso_2, l_hip_3, r_hip_3 links mass in the URDF was set to 0, and so SDF stops converting (silently, so this could be in a sense a bug in sdformat) the model as soon as a massless links was reached. As the support/effort is now placed in using the iCub models automatically generated from CAD models, I think we can safely closed this issue.