概要

本パッケージには、ロボットのモデル、センサー、シーンなどのXML仕様が多数含まれています。 各XML仕様には、1つまたは複数の言語で対応するパーサーがあります。

Components

New in Hydro urdfを構成するのは、さまざまなパッケージやコンポーネントです。下図は、これらのコンポーネントの関係を説明しようとするものです。

Current Status of URDF Components in Hydro:

• The core URDF parser and data structures (urdfdom, urdfdom_headers) have been pushed upstream into stand alone (no ROS-dependencies) software packages that will in the future be released into Ubuntu completely separate from ROS.
• There is now a distinction between a URDF file and a URDF data structure. A URDF file follows the XML format as described on the ros.org wiki. A URDF data structure is a set of generic classes that various formats (currently URDF and Collada) can be parsed into.
• A new plugin abstraction layer (urdf_parser_plugin) allows the URDF data structures to be populated with various file formats (currently URDF and Collada)
• The ROS packages urdf_parser and urdf_interface have been deprecated in Groovy and removed in Hydro.

Getting Started

There is large set of tutorials on how to build up your own robot models using the URDF specification. Check out the ja/urdf/Tutorials page.

We also developed a macro language called xacro to make it easier to maintain the robot description files, increase their readability, and to avoid duplication in the robot description files.

Examples

See this page for a list of robots described by a URDF model.

Tools

Verification

A command line tool check_urdf attempts to parse a file as a URDF description, and either prints a description of the resulting kinematic chain, or an error message.

For example, to run this tool on the pr2 urdf, first create the urdf file by running:

• rosrun xacro xacro.py `rospack find pr2_description`/robots/pr2.urdf.xacro -o /tmp/pr2.urdf

New in Indigo

Then run the check by running:

Note: You may need to run sudo apt-get install liburdfdom-tools.

• check_urdf pr2.urdf

New in Hydro

Then run the check by running:

• rosrun urdfdom check_urdf /tmp/pr2.urdf

  and you should see something resembling:

  robot name is: pr2
  ---------- Successfully Parsed XML ---------------
  root Link: base_footprint has 1 child(ren)
      child(1):  base_link
          child(1):  base_laser_link
          child(2):  bl_caster_rotation_link
              child(1):  bl_caster_l_wheel_link
              child(2):  bl_caster_r_wheel_link
          child(3):  br_caster_rotation_link
              child(1):  br_caster_l_wheel_link
              child(2):  br_caster_r_wheel_link
          child(4):  fl_caster_rotation_link
              child(1):  fl_caster_l_wheel_link
              child(2):  fl_caster_r_wheel_link
          child(5):  fr_caster_rotation_link
              child(1):  fr_caster_l_wheel_link
              child(2):  fr_caster_r_wheel_link
          child(6):  torso_lift_link
              child(1):  head_pan_link
                  child(1):  head_tilt_link
                      child(1):  head_plate_frame
                          child(1):  sensor_mount_link
                              child(1):  double_stereo_link
                                  child(1):  narrow_stereo_link
   ...

Visualization

To get a graphviz diagram of your urdf file, do the following:

New in Indigo In Indigo, the urdf_to_graphiz tool has moved to the liburdfdom-tools package. You may need to run sudo apt-get install liburdfdom-tools if you can't use urdf_to_graphiz

• urdf_to_graphiz pr2.urdf

New in Hydro

• urdf_to_graphiz pr2.urdf

The result is a file called pr2.pdf that looks something like this:

Known Issues

• Sensor model information is not included (except in gazebo extensions for simulated sensors).