[ros2] Different interpretation of xacro/urdf files between igniton-gazebo3 and igniton-gazebo4/5

[doisyg]

Environment

• OS Version: Ubuntu 20.04
• Source or binary build: igniton-gazebo3 igniton-gazebo4 igniton-gazebo5

Description

Don't know if I should report here or there: https://github.com/ignitionrobotics/ign-gazebo
I have a ROS / Ignition robot simulation working well with citadel, I did few tests with the newly released edifice and run into an issue on how my xacro/files are interpreted by gazebo when spawning with ros_ign_gazebo create.
More specifically on how a lidar sensor is positioned by gazebo.
When interpreting the following xacro/urdf file:

<?xml version="1.0" ?>
<robot name="will_be_ignored" xmlns:xacro="http://www.ros.org/wiki/xacro">

<gazebo>
  <plugin filename="ignition-gazebo-sensors-system" name="ignition::gazebo::systems::Sensors">
    <render_engine>ogre2</render_engine>
  </plugin>
</gazebo>

<link name="base_footprint">
  <visual>
    <geometry>
      <sphere radius="0.5"/>
    </geometry>
  </visual>
  <collision>
    <geometry>
      <sphere radius="0.5"/>
    </geometry>
  </collision>
  <inertial>
    <mass value="1"/>
  <inertia ixx="1" ixy="0.0" ixz="0.0" iyy="1" iyz="0.0" izz="1"/>
  </inertial>
</link>

<link name="link">
  <visual>
    <geometry>
      <sphere radius="1.0"/>
    </geometry>
  </visual>
  <collision>
    <geometry>
      <sphere radius="1.0"/>
    </geometry>
  </collision>
  <inertial>
    <mass value="1"/>
    <inertia ixx="1" ixy="0.0" ixz="0.0" iyy="1" iyz="0.0" izz="1"/>
  </inertial>
</link>

<gazebo reference="link" >
  <sensor name="link" type="gpu_lidar">
    <topic>scan</topic>
    <update_rate>30</update_rate>
    <lidar>
      <scan>
        <horizontal>
          <samples>2800</samples>
          <resolution>1</resolution>
          <min_angle>-2.09</min_angle>
          <max_angle>2.09</max_angle>
        </horizontal>
        <vertical>
          <samples>1</samples>
          <resolution>0.1</resolution>
          <min_angle>0.0</min_angle>
          <max_angle>0.0</max_angle>
        </vertical>
      </scan>
      <range>
        <min>0.05</min>
        <max>30.0</max>
        <resolution>0.01</resolution>
      </range>
    </lidar>
    <alwaysOn>1</alwaysOn>
    <visualize>true</visualize>
  </sensor>
</gazebo>

<joint name="base_footprint_joint" type="fixed">
  <origin xyz="0 0 3.0" rpy="0 0 0" />
  <parent link="base_footprint"/>
  <child link="link" />
</joint>

</robot>

igniton-gazebo3 places properly the lidar sensor at the origin of the link "link", whereas igniton-gazebo4 and igniton-gazebo5 place it at the origin of the link "base_footprint"

And indeed, if I use the gazebo GUI feature "Save world as..." I get a different sdf file between igniton-gazebo3 and igniton-gazebo4/5. With igniton-gazebo3, the sensor has the attribute <pose>0 0 3 0 -0 0</pose>, whereas with igniton-gazebo4/5, the sensor has no pose attribute. Full sdf files below:

igniton-gazebo3 :

<sdf version='1.7'>
  <world name='empty'>
    <physics name='1ms' type='ignored'>
      <max_step_size>0.001</max_step_size>
      <real_time_factor>1</real_time_factor>
      <real_time_update_rate>1000</real_time_update_rate>
    </physics>
    <plugin name='ignition::gazebo::systems::Physics' filename='ignition-gazebo-physics-system'/>
    <plugin name='ignition::gazebo::systems::UserCommands' filename='ignition-gazebo-user-commands-system'/>
    <plugin name='ignition::gazebo::systems::SceneBroadcaster' filename='ignition-gazebo-scene-broadcaster-system'/>
    <plugin name='ignition::gazebo::systems::Contact' filename='ignition-gazebo-contact-system'/>
    <light name='sun' type='directional'>
      <cast_shadows>1</cast_shadows>
      <pose>0 0 10 0 -0 0</pose>
      <diffuse>0.8 0.8 0.8 1</diffuse>
      <specular>0.2 0.2 0.2 1</specular>
      <attenuation>
        <range>1000</range>
        <constant>0.9</constant>
        <linear>0.01</linear>
        <quadratic>0.001</quadratic>
      </attenuation>
      <direction>-0.5 0.1 -0.9</direction>
      <spot>
        <inner_angle>0</inner_angle>
        <outer_angle>0</outer_angle>
        <falloff>0</falloff>
      </spot>
    </light>
    <gravity>0 0 -9.8</gravity>
    <magnetic_field>6e-06 2.3e-05 -4.2e-05</magnetic_field>
    <atmosphere type='adiabatic'/>
    <scene>
      <ambient>0.4 0.4 0.4 1</ambient>
      <background>0.7 0.7 0.7 1</background>
      <shadows>1</shadows>
    </scene>
    <model name='ground_plane'>
      <static>1</static>
      <link name='link'>
        <collision name='collision'>
          <geometry>
            <plane>
              <normal>0 0 1</normal>
              <size>100 100</size>
            </plane>
          </geometry>
          <surface>
            <friction>
              <ode/>
            </friction>
            <contact/>
          </surface>
        </collision>
        <visual name='visual'>
          <geometry>
            <plane>
              <normal>0 0 1</normal>
              <size>100 100</size>
            </plane>
          </geometry>
          <material>
            <ambient>0.8 0.8 0.8 1</ambient>
            <diffuse>0.8 0.8 0.8 1</diffuse>
            <specular>0.8 0.8 0.8 1</specular>
          </material>
          <plugin name='__default__' filename='__default__'/>
        </visual>
      </link>
      <plugin name='__default__' filename='__default__'/>
      <pose>0 0 0 0 -0 0</pose>
    </model>
    <model name='my_custom_model'>
      <link name='base_footprint'>
        <inertial>
          <pose>0 0 1.5 0 -0 0</pose>
          <mass>2</mass>
          <inertia>
            <ixx>6.5</ixx>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyy>6.5</iyy>
            <iyz>0</iyz>
            <izz>2</izz>
          </inertia>
        </inertial>
        <collision name='base_footprint_collision'>
          <pose>0 0 0 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>0.5</radius>
            </sphere>
          </geometry>
          <surface>
            <friction>
              <ode/>
            </friction>
            <contact/>
          </surface>
        </collision>
        <collision name='base_footprint_fixed_joint_lump__link_collision_1'>
          <pose>0 0 3 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>1</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode/>
            </contact>
            <friction>
              <ode/>
            </friction>
          </surface>
        </collision>
        <visual name='base_footprint_visual'>
          <pose>0 0 0 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>0.5</radius>
            </sphere>
          </geometry>
          <plugin name='__default__' filename='__default__'/>
        </visual>
        <visual name='base_footprint_fixed_joint_lump__link_visual_1'>
          <pose>0 0 3 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>1</radius>
            </sphere>
          </geometry>
          <plugin name='__default__' filename='__default__'/>
        </visual>
        <gravity>1</gravity>
        <velocity_decay/>
        <sensor name='link' type='gpu_lidar'>
          <topic>scan</topic>
          <update_rate>30</update_rate>
          <lidar>
            <scan>
              <horizontal>
                <samples>2800</samples>
                <resolution>1</resolution>
                <min_angle>-2.09</min_angle>
                <max_angle>2.09</max_angle>
              </horizontal>
              <vertical>
                <samples>1</samples>
                <resolution>0.1</resolution>
                <min_angle>0</min_angle>
                <max_angle>0</max_angle>
              </vertical>
            </scan>
            <range>
              <min>0.05</min>
              <max>30</max>
              <resolution>0.01</resolution>
            </range>
          </lidar>
          <visualize>1</visualize>
          <pose>0 0 3 0 -0 0</pose>
          <alwaysOn>1</alwaysOn>
          <plugin name='__default__' filename='__default__'/>
        </sensor>
      </link>
      <static>0</static>
      <plugin name='ignition::gazebo::systems::Sensors' filename='ignition-gazebo-sensors-system'>
        <render_engine>ogre2</render_engine>
      </plugin>
      <pose>1.2 0 0.5 0 -0 -2.88319</pose>
    </model>
  </world>
</sdf>

and with igniton-gazebo5 :

<sdf version='1.8'>
  <world name='empty'>
    <physics name='1ms' type='ignored'>
      <max_step_size>0.001</max_step_size>
      <real_time_factor>1</real_time_factor>
      <real_time_update_rate>1000</real_time_update_rate>
    </physics>
    <plugin name='ignition::gazebo::systems::Physics' filename='ignition-gazebo-physics-system'/>
    <plugin name='ignition::gazebo::systems::UserCommands' filename='ignition-gazebo-user-commands-system'/>
    <plugin name='ignition::gazebo::systems::SceneBroadcaster' filename='ignition-gazebo-scene-broadcaster-system'/>
    <plugin name='ignition::gazebo::systems::Contact' filename='ignition-gazebo-contact-system'/>
    <light name='sun' type='directional'>
      <cast_shadows>1</cast_shadows>
      <pose>0 0 10 0 -0 0</pose>
      <diffuse>0.8 0.8 0.8 1</diffuse>
      <specular>0.2 0.2 0.2 1</specular>
      <attenuation>
        <range>1000</range>
        <constant>0.90000000000000002</constant>
        <linear>0.01</linear>
        <quadratic>0.001</quadratic>
      </attenuation>
      <direction>-0.5 0.1 -0.9</direction>
      <spot>
        <inner_angle>0</inner_angle>
        <outer_angle>0</outer_angle>
        <falloff>0</falloff>
      </spot>
    </light>
    <gravity>0 0 -9.8</gravity>
    <magnetic_field>6e-06 2.3e-05 -4.2e-05</magnetic_field>
    <atmosphere type='adiabatic'/>
    <scene>
      <ambient>0.4 0.4 0.4 1</ambient>
      <background>0.7 0.7 0.7 1</background>
      <shadows>1</shadows>
    </scene>
    <model name='ground_plane'>
      <static>1</static>
      <link name='link'>
        <collision name='collision'>
          <geometry>
            <plane>
              <normal>0 0 1</normal>
              <size>100 100</size>
            </plane>
          </geometry>
          <surface>
            <friction>
              <ode/>
            </friction>
            <bounce/>
            <contact/>
          </surface>
        </collision>
        <visual name='visual'>
          <geometry>
            <plane>
              <normal>0 0 1</normal>
              <size>100 100</size>
            </plane>
          </geometry>
          <material>
            <ambient>0.8 0.8 0.8 1</ambient>
            <diffuse>0.8 0.8 0.8 1</diffuse>
            <specular>0.8 0.8 0.8 1</specular>
          </material>
          <plugin name='__default__' filename='__default__'/>
        </visual>
      </link>
      <plugin name='__default__' filename='__default__'/>
      <pose>0 0 0 0 -0 0</pose>
    </model>
    <model name='my_custom_model'>
      <link name='base_footprint'>
        <inertial>
          <pose>0 0 1.5 0 -0 0</pose>
          <mass>2</mass>
          <inertia>
            <ixx>6.5</ixx>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyy>6.5</iyy>
            <iyz>0</iyz>
            <izz>2</izz>
          </inertia>
        </inertial>
        <collision name='base_footprint_collision'>
          <pose>0 0 0 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>0.5</radius>
            </sphere>
          </geometry>
          <surface>
            <friction>
              <ode/>
            </friction>
            <bounce/>
            <contact/>
          </surface>
        </collision>
        <collision name='base_footprint_fixed_joint_lump__link_collision_1'>
          <pose>0 0 3 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>1</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode/>
            </contact>
            <friction>
              <ode/>
            </friction>
            <bounce/>
          </surface>
        </collision>
        <visual name='base_footprint_visual'>
          <pose>0 0 0 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>0.5</radius>
            </sphere>
          </geometry>
          <plugin name='__default__' filename='__default__'/>
        </visual>
        <visual name='base_footprint_fixed_joint_lump__link_visual_1'>
          <pose>0 0 3 0 -0 0</pose>
          <geometry>
            <sphere>
              <radius>1</radius>
            </sphere>
          </geometry>
          <plugin name='__default__' filename='__default__'/>
        </visual>
        <gravity>1</gravity>
        <velocity_decay/>
        <sensor name='link' type='gpu_lidar'>
          <topic>scan</topic>
          <update_rate>30</update_rate>
          <lidar>
            <scan>
              <horizontal>
                <samples>2800</samples>
                <resolution>1</resolution>
                <min_angle>-2.0899999999999999</min_angle>
                <max_angle>2.0899999999999999</max_angle>
              </horizontal>
              <vertical>
                <samples>1</samples>
                <resolution>0.10000000000000001</resolution>
                <min_angle>0</min_angle>
                <max_angle>0</max_angle>
              </vertical>
            </scan>
            <range>
              <min>0.050000000000000003</min>
              <max>30</max>
              <resolution>0.01</resolution>
            </range>
          </lidar>
          <visualize>1</visualize>
          <alwaysOn>1</alwaysOn>
          <plugin name='__default__' filename='__default__'/>
        </sensor>
      </link>
      <static>0</static>
      <plugin name='ignition::gazebo::systems::Sensors' filename='ignition-gazebo-sensors-system'>
        <render_engine>ogre2</render_engine>
      </plugin>
      <pose>1.2 0 0.5 0 -0 -2.88319</pose>
    </model>
  </world>
</sdf>

[chapulina]

I suspect this may be related to changes from libSDFormat 9 (Citadel) to libSDFormat 10 (Dome), because that's where the URDF gets parsed into SDF. In fact, a quicker way of reproducing this can be achieved with the ign sdf tool:

Citadel has the sensor pose:

ign sdf --force-version 9.5.0 -p /tmp/urdf

<sdf version='1.7'>
  <model name='will_be_ignored'>
    <link name='base_footprint'>
      <inertial>
        <pose>0 0 1.5 0 -0 0</pose>
        <mass>2</mass>
        <inertia>
          <ixx>6.5</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>6.5</iyy>
          <iyz>0</iyz>
          <izz>2</izz>
        </inertia>
      </inertial>
      <collision name='base_footprint_collision'>
        <pose>0 0 0 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>0.5</radius>
          </sphere>
        </geometry>
      </collision>
      <collision name='base_footprint_fixed_joint_lump__link_collision_1'>
        <pose>0 0 3 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>1</radius>
          </sphere>
        </geometry>
        <surface>
          <contact>
            <ode/>
          </contact>
          <friction>
            <ode/>
          </friction>
        </surface>
      </collision>
      <visual name='base_footprint_visual'>
        <pose>0 0 0 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>0.5</radius>
          </sphere>
        </geometry>
      </visual>
      <visual name='base_footprint_fixed_joint_lump__link_visual_1'>
        <pose>0 0 3 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>1</radius>
          </sphere>
        </geometry>
      </visual>
      <gravity>1</gravity>
      <velocity_decay/>
      <sensor name='link' type='gpu_lidar'>
        <topic>scan</topic>
        <update_rate>30</update_rate>
        <lidar>
          <scan>
            <horizontal>
              <samples>2800</samples>
              <resolution>1</resolution>
              <min_angle>-2.09</min_angle>
              <max_angle>2.09</max_angle>
            </horizontal>
            <vertical>
              <samples>1</samples>
              <resolution>0.1</resolution>
              <min_angle>0</min_angle>
              <max_angle>0</max_angle>
            </vertical>
          </scan>
          <range>
            <min>0.05</min>
            <max>30</max>
            <resolution>0.01</resolution>
          </range>
        </lidar>
        <visualize>1</visualize>
        <pose>0 0 3 0 -0 0</pose>
        <alwaysOn>1</alwaysOn>
      </sensor>
    </link>
    <static>0</static>
    <plugin name='ignition::gazebo::systems::Sensors' filename='ignition-gazebo-sensors-system'>
      <render_engine>ogre2</render_engine>
    </plugin>
  </model>
</sdf>

Dome doesn't:

ign sdf --force-version 10.3.0 -p /tmp/urdf

<sdf version='1.7'>
  <model name='will_be_ignored'>
    <link name='base_footprint'>
      <inertial>
        <pose>0 0 1.5 0 -0 0</pose>
        <mass>2</mass>
        <inertia>
          <ixx>6.5</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>6.5</iyy>
          <iyz>0</iyz>
          <izz>2</izz>
        </inertia>
      </inertial>
      <collision name='base_footprint_collision'>
        <pose>0 0 0 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>0.5</radius>
          </sphere>
        </geometry>
      </collision>
      <collision name='base_footprint_fixed_joint_lump__link_collision_1'>
        <pose>0 0 3 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>1</radius>
          </sphere>
        </geometry>
        <surface>
          <contact>
            <ode/>
          </contact>
          <friction>
            <ode/>
          </friction>
        </surface>
      </collision>
      <visual name='base_footprint_visual'>
        <pose>0 0 0 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>0.5</radius>
          </sphere>
        </geometry>
      </visual>
      <visual name='base_footprint_fixed_joint_lump__link_visual_1'>
        <pose>0 0 3 0 -0 0</pose>
        <geometry>
          <sphere>
            <radius>1</radius>
          </sphere>
        </geometry>
      </visual>
      <gravity>1</gravity>
      <velocity_decay/>
      <sensor name='link' type='gpu_lidar'>
        <topic>scan</topic>
        <update_rate>30</update_rate>
        <lidar>
          <scan>
            <horizontal>
              <samples>2800</samples>
              <resolution>1</resolution>
              <min_angle>-2.09</min_angle>
              <max_angle>2.09</max_angle>
            </horizontal>
            <vertical>
              <samples>1</samples>
              <resolution>0.1</resolution>
              <min_angle>0</min_angle>
              <max_angle>0</max_angle>
            </vertical>
          </scan>
          <range>
            <min>0.05</min>
            <max>30</max>
            <resolution>0.01</resolution>
          </range>
        </lidar>
        <visualize>1</visualize>
        <alwaysOn>1</alwaysOn>
      </sensor>
    </link>
    <static>0</static>
    <plugin name='ignition::gazebo::systems::Sensors' filename='ignition-gazebo-sensors-system'>
      <render_engine>ogre2</render_engine>
    </plugin>
  </model>
</sdf>

Looking through SDFormat's changelog, nothing stood out as being the culprit though.

[scpeters]

I believe this is connected to fixed-joint reduction with the libsdformat parser_urdf.cc file

[chapulina]

I think this was fixed by gazebosim/sdformat#525

[doisyg]

Hopefully. It looks like it is related. Will test once merged or released in sdf11

[doisyg]

Confirmed fixed in dome/sdf10, still need a merge in edifice/sdf11

[chapulina]

The SDFormat fix has been forward-ported to Edifice. I'm closing this. ROS users will get the updated versions as the fix is released and ported to packages.ros.org.