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Overview

This package contains a number of XML specifications for robot models, sensors, scenes, etc. Each XML specification has a corresponding parser in one or more languages.

Getting Started

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

The robot model stack includes the command line tool check_urdf. It's called with a single command line argument naming a file. It attempts to parse the 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

Then run the check by running:

• rosrun urdf check_urdf /tmp/pr2.urdf

Groovy:

• 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 this:

• rosrun urdf_parser urdf_to_graphiz /tmp/pr2.urdf

Groovy:

• rosrun urdfdom urdf_to_graphiz /tmp/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).