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2017-03-09 02:16:01 -0500 commented answer Gazebo contact sensor added to a robot link in urdf file is not working as expected?

Sure and thanks for that. I was just pointing out that I added the issue reference yesterday (I completely forgot to add it before).

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2017-03-08 03:12:31 -0500 commented answer Gazebo contact sensor added to a robot link in urdf file is not working as expected?

I've already created an issue which describes the same behavior exactly one year ago, but it is still not assigned. You can find it here: https://bitbucket.org/osrf/sdformat/issues/113/parsing-from-urdf-to-sdf-does-not-handle. Follow the linked repository for details.

2017-03-08 03:04:29 -0500 commented question Problems while parsing <gazebo> URDF elements with Gazebo7 and ROS Jade

Sorry for not updating the post, I've created an issue which describes the same behavior exactly one year ago, but it is still not assigned. You can find it here: https://bitbucket.org/osrf/sdformat/issues/113/parsing-from-urdf-to-sdf-does-not-handle

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2016-02-26 02:54:08 -0500 commented question Problems while parsing <gazebo> URDF elements with Gazebo7 and ROS Jade

Thank you. I've just made some tests again after the realease (this morning) of `ros-jade-gazebo7-ros-pkgs`, but it has still the same behaviour...

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2016-02-22 04:48:56 -0500 asked a question Problems while parsing <gazebo> URDF elements with Gazebo7 and ROS Jade

I use Gazebo 7 with ROS Jade for which ros-jade-gazebo7-ros-pkgs cannot yet be installed (due to the dependency to ros-jade-gazebo7-plugins which does not exist). Thus, I've cloned the jade-devel branch of the gazebo_ros_pkgs package in the catkin workspace and compiled it with catkin_make. EDITED after ros-jade-gazebo7-ros-pkgs release: still the same behaviour.


Issue created on 2016/03/08

Check the details in the issue and follow the linked repository: https://bitbucket.org/osrf/sdformat/i...


Update 2016/03/01

I've been investigated more on this problem and I've found out that it could be due to the new naming convention from Gazebo 6 on.* I've tried the example below with ROS Jade and Gazebo 5, 6 and 7 and it works only with the first one (which relies on *sdformat2).

Using sdformat3 and sdformat4, <visual> and <collision> elements get augmented unique names when they are converted to SDF (which differ from those given in the URDF). Indeed, using <gazebo> tags it is possible to add any element which will not end in <visual> or <collision> elements, e.g. <enable_wind> or <velocity_decay> which are directly children of the <link> tag.

On the other hand, every element which has to be put inside <visual> or <collision> is completely ignored (without errors) from the parser. I think that it expects to use the URDF visual/collision names but they differ, e.g. visual_waist and collision_waist are the name in the URDF and the respectively SDF ones are waist_fixed_joint_lump__visual_waist_visual and waist_fixed_joint_lump__collision_waist_collision.

Should I report this bug on https://bitbucket.org/osrf/sdformat/o... ?


Example

I have made a simple example (download) to show that (at least with my configuration) elements inside <gazebo> urdf tags are not correctly parsed by either spawn_model or gz sdf -p commands.

I followed this Gazebo tutorial: Using a URDF in Gazebo.

This is the package structure inside my caktkin workspace:

/robot:
  /robot_description:
    /urdf:
      robot.gazebo
      robot.urdf
      robot.xacro
    CMakeLists.txt
    package.xml
  /robot_gazebo:
    /launch:
      robot_world.launch
    /worlds:
      robot.world
    CMakeLists.txt
    package.xml

where robot.world is a simple empty world and robot_world.launch contains the URDF spawner:

<param name="robot_description"
       command="$(find xacro)/xacro --inorder '$(find robot_description)/urdf/robot.xacro'"/>

<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen" 
      args="-urdf -model robot -param robot_description"/>

and where the file in the /urdf folder are as follow:

robot.xacro

<?xml version="1.0"?>
<robot name="robot" xmlns:xacro="http://www.ros.org/wiki/xacro">
  <!-- imports all Gazebo-customization elements, including Gazebo colors -->
  <xacro:include filename="$(find robot_description)/urdf/robot.gazebo"/>
  <!-- imports URDF robot model -->
  <xacro:include filename="$(find robot_description)/urdf/robot.urdf"/>
</robot>

robot.urdf

<?xml version="1.0"?>
<robot name="robot">

  <link name="pelvis">
    <inertial>
      <origin xyz="-1e-06 0.060095 -0.014315" rpy="0 0 0"/>
      <mass value="2.468"/>
      <inertia ixx="0.015171" ixy="0" ixz="0" iyy="0.022628" iyz="0" izz="0.018252"/>
    </inertial>
    <visual name="visual_pelvis">
      <origin xyz="-4.5e-05 0.021 -0.01302" rpy="0 0 0"/>
      <geometry ...
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2016-02-18 13:26:17 -0500 commented answer URDF to Gazebo differs from URDF to SDF to Gazebo

Yes sorry, I've already seen it. I was talking about something like the ones in Brosseau answer; they should appear in the SDF as told in the tutorial, aren't they?

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2016-02-18 03:15:21 -0500 commented answer URDF to Gazebo differs from URDF to SDF to Gazebo

I've tried your proposal, but nothing appears in the SDF even if it is said in the tutorial above that "[...] any arbitrary blobs that are not parsed according to the table above are inserted into the the corresponding <link> element in the SDF.".

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2016-02-18 03:11:28 -0500 commented answer URDF to Gazebo differs from URDF to SDF to Gazebo

Thank you very much, I didn't see those options! At least the model pose is fine now, even if I still don't get why some parameters in the <gazebo> tags are not passed to the SDF model... I'll open another question in the next few days with a code example.

2016-02-17 15:52:07 -0500 commented question URDF to Gazebo differs from URDF to SDF to Gazebo

What would you suggest now? Switch to Gazebo 6? Create two distinct models (SDF only for Gazebo simulation and URDF for control purposes) even if this would mean update twice when modifying something in the model? Or even other advices?

2016-02-17 15:51:47 -0500 commented question URDF to Gazebo differs from URDF to SDF to Gazebo

Thanks @hsu, I probably got the problem: as I said in http://answers.ros.org/question/226659/ros-jade-gazebo7-and-gazebo_ros_control-compatibility/ I compiled directly the `jade-devel` branch of `gazebo_ros_pkgs` because there is no `gazebo_ros_pkgs` for ROS Jade and Gazebo7 yet. I thought that it was quite fine because I could control my robot from ROS as explained in the tutorials, but now I believe that the `spawn_model` could be a bit dated. Why `gz sdf` and `spawn_model` use distinct code?

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2016-02-17 08:56:04 -0500 commented answer URDF to Gazebo differs from URDF to SDF to Gazebo

I had tried with those specified in the tutorial: http://gazebosim.org/tutorials?tut=ros_urdf&cat=connect_ros#<gazebo>ElementsForLinks and http://gazebosim.org/tutorials?tut=ros_urdf&cat=connect_ros#<gazebo>ElementsForJoints. I'll try this evening with your proposal. Thanks for now.

2016-02-17 03:25:03 -0500 commented question URDF to Gazebo differs from URDF to SDF to Gazebo

Nothing happens, but no warning is displayed this time... At a closer look it seems that no properties in the `<gazebo>` tags pass from the URDF to Gazebo (I've specified frictional parameters but they are filled with default values), even if the `gazebo_ros_control` plugin is properly loaded... I'm using Gazebo7 with ROS Jade; could this be a problem?

2016-02-16 15:55:28 -0500 asked a question URDF to Gazebo differs from URDF to SDF to Gazebo

I found out a strange behaviour when spawning model in Gazebo.

I have an URDF model of a humanoid robot and a launch file where it is sapwned to Gazebo through model_spawn of the gazebo_ros package using -urdf flag:

<param name="robot_description" 
       command="$(find xacro)/xacro.py '$(find my_robot_description)/urdf/my_robot.xacro'"/>
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
      args="-urdf -model my_robot -param robot_description"/>

In such a case, if I endow the URDF with a simple <gazebo> property as follows:

<gazebo>
  <!-- robot model offset -->
  <pose>0 0 0.5 0 0 0</pose>
</gazebo>

It doesn't affect my model in Gazebo, which generate a warning like this:

Warning [parser_urdf.cc:1232] multiple inconsistent <pose> exists due to fixed joint reduction overwriting previous value [0 0 0.5 0 0 0] with [0 0 0 0 -0 0].

However, if I convert the URDF first to SDF (using gz sdf -p my_robot.urdf) and spawn the SDF directly with the -sdf flag, this does not happen and everything works as expected.

Why does this happen? Is a problem of the URDF parser of Gazebo or I'm doing something wrong?