urdfdom

The URDF (U-Robot Description Format) library provides core data structures and a simple XML parsers for populating the class data structures from an URDF file.

For now, the details of the URDF specifications reside on http://ros.org/wiki/urdf

Using with ROS

If you choose to check this repository out for use with ROS, be aware that the necessary package.xml is not included in this repo but instead is added in during the ROS release process. To emulate this, pull the appropriate file into this repository using the following format. Be sure to replace the ALLCAPS words with the appropriate terms:

wget https://raw.github.com/ros-gbp/urdfdom-release/debian/ROS_DISTRO/UBUNTU_DISTRO/urdfdom/package.xml

For example:

wget https://raw.github.com/ros-gbp/urdfdom-release/debian/hydro/precise/urdfdom/package.xml

URDF Versioning

The URDF format supports versioning to allow for format evolution while maintaining compatibility. The version is specified in the <robot> tag using the version attribute in the format x.y (e.g., "1.0", "1.1").

Supported Versions

Version 1.0 (Default)

Version 1.0 is the default URDF version. When the version attribute is omitted from the <robot> tag, the parser assumes version 1.0.

Features supported in version 1.0:

• Robot model definition (links, joints, materials)
• Visual and collision geometry (box, cylinder, sphere, mesh)
• Joint types: revolute, continuous, prismatic, fixed, floating, planar
• Pose specification using xyz and rpy (roll-pitch-yaw) attributes
• Transmission elements
• Gazebo extensions and many more

Example:

<robot name="my_robot">
  <!-- No version attribute means version 1.0 -->
  <link name="base_link"/>
</robot>

Or explicitly:

<robot name="my_robot" version="1.0">
  <link name="base_link"/>
</robot>

Version 1.1

Version 1.1 extends the URDF specification with the following new features:

• All features from version 1.0
• Quaternion orientation: The quat_xyzw attribute can be used in <origin> elements as an alternative to rpy for specifying orientation
• Capsule geometry: A new geometry primitive defined by radius and length attributes

Quaternion Example:

<robot name="my_robot" version="1.1">
  <link name="base_link">
    <visual>
      <origin xyz="0 0 0" quat_xyzw="0 0 0 1"/>
      <geometry>
        <box size="1 1 1"/>
      </geometry>
    </visual>
  </link>
</robot>

Note: You cannot use both rpy and quat_xyzw in the same <origin> element.

Capsule Geometry Example:

<robot name="my_robot" version="1.1">
  <link name="arm_link">
    <visual>
      <geometry>
        <capsule radius="0.05" length="0.5"/>
      </geometry>
    </visual>
    <collision>
      <geometry>
        <capsule radius="0.05" length="0.5"/>
      </geometry>
    </collision>
  </link>
</robot>

File truncated at 100 lines see the full file

Changelog for package urdfdom

5.1.0 (2026-02-06)

• Support for URDF Specification 1.1

  • Add support for capsule geometry type (#238)

    • Add documentation about versioning

    * Require version 2.1.0 of urdfdom_headers Co-authored-by: Steve Peters <<scpeters@openrobotics.org>>

  • Support quaternions in URDF 1.1 (#235) Co-authored-by: Guillaume Doisy <<doisyg@users.noreply.github.com>>

• Fix multiple format-string vulnerabilities in URDF parser logging (#243) User-controlled URDF content was passed directly to CONSOLE_BRIDGE_logError() at multiple call sites, allowing printf-style format string interpretation. All affected logging paths now use explicit "%s" format specifiers to ensure input is treated as data and to prevent information disclosure or undefined behavior.

• More logging format string fixes (#244)

  • Add explicit "%s" format strings when logging
  • Use %s format string instead of string addition

• Read cmake version from package.xml (#236)

  * Use regex to match version string. Based on suggestion from Chris Lalancette.

  * Require cmake minimum version 3.10 Co-authored-by: Chris Lalancette <<clalancette@gmail.com>>

• Contributors: Florencia, Sai Kishor Kothakota, Steve Peters

5.0.4 (2025-12-08)

• Revert "Quaternion in urdf (PR123 new attempt) (#231)" (#231)
• Contributors: Steve Peters

5.0.3 (2025-11-28)

• Quaternion in urdf (PR123 new attempt) (#194)
• Removed tinyxml2_vendor dependency (#225)
• Contributors: Alejandro Hernández Cordero, Guillaume Doisy

5.0.2 (2025-07-03)

• Relax the version compatibility for urdfdom_headers. (#222)
• Contributors: Chris Lalancette

5.0.1 (2025-07-01)

4.0.3 (2025-06-23)

• Removed deprecated code (#217)
• Remove ROS 1 workflows and update ROS 2 (#218)
• Improvements for the URDF xsd specification (#200)
• Update ros2.yaml (#214)
• fix: missing header (#216)
• Contributors: Alejandro Hernández Cordero, Amin Ya, Pierre Ballif, mosfet80