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Problems spawning PR2

asked 2014-07-18 06:11:00 -0600

elias gravatar image

updated 2014-07-18 06:39:32 -0600

Hi,

I have a problem following the instructions given in this tutorial.

I have a plain vanilla hydro installation and followed the tutorial step by step. I ran in some problems I was able to work around. But spawning the PR2 in the newly created world with the gas-station fails and I cannot find the reason...

My pr2-gasstation.launch looks like this:

<!-- Convert an xacro and put on parameter server -->
<param name="robot_description" command="$(find xacro)/xacro.py $(find pr2_description)/robots/pr2.urdf.xacro" />

<!-- Spawn a robot into Gazebo -->
<node name="spawn_urdf" pkg="gazebo_ros" type="spawn_model" args="-param robot_description -urdf -model pr2" />

<launch>
  <!-- We resume the logic in empty_world.launch, changing only the name of the world to be launched -->
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="$(find pr2_gazebo)/worlds/pr2.world"/>
    <!-- more default parameters can be changed here -->
  </include>
</launch>

I got this error:

Invalid roslaunch XML syntax: junk after document element: line 5, column 0

I checked if the command of line 2 is working on my machine and discovered after resolving the paths by hand that the .urdf seems to be created in the console. Unfortunately line 5 seems to have still a problem...

I also checked if pr2_empty_world.launch is working and I can confirm that this launches the PR2 in an empty world. However, the other predefined scenarios which comes with the ros-hydro-pr2-common e.g. pr2_table_object.launch does not launch properly resulting in the following error:

Invalid <arg> tag: arg 'gui' has already been declared. 

Arg xml is <arg default="true" name="gui"/>

I checked all the others but the empty world is the only one which actually launches the simulator with the robot.

Any help is very appreciated. Thank you in advance.

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answered 2014-07-21 02:31:38 -0600

Hi elias,

your launch file structure is wrong.

<launch>
  <!-- Convert an xacro and put on parameter server -->
  <param name="robot_description" command="$(find xacro)/xacro.py $(find pr2_description)/robotspr2.urdf.xacro" />

  <!-- Spawn a robot into Gazebo -->
  <node name="spawn_urdf" pkg="gazebo_ros" type="spawn_model" args="-param robot_description -urdf-model pr2" />

  <!-- We resume the logic in empty_world.launch, changing only the name of the world to be launched -->
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="$(find pr2_gazebo)/worlds/pr2.world"/>
    <!-- more default parameters can be changed here -->
  </include>
</launch>

the launch file should always have a root element <launch/> the ros wiki contains a good description about roslaunch files...

I have no idea about the second failure but it seems like one file is containing more that one line declaring the gui argument...

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Thanks. Now I have a PR2 in a gas-station. :) I am still confused with the second problem. But thanks for the advise.

elias gravatar imageelias ( 2014-07-21 06:46:44 -0600 )edit

Thanks. Now I have a PR2 in a gas-station. :)

elias gravatar imageelias ( 2014-07-21 06:46:46 -0600 )edit
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Asked: 2014-07-18 06:11:00 -0600

Seen: 1,706 times

Last updated: Jul 21 '14