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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.

XML Description



XML Schema



Parser API Model API

Model API





New in Hydro A number of different packages and components make up urdf. The following diagram attempts to explain the relationship between these components:


Current Status of URDF Components 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 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.


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



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:

New in Indigo

Then run the check by running:

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

New in Hydro

Then run the check by running:


Visual Studio Code has a ROS extension that supports URDF 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

New in Hydro

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


Creating URDF

URDF is XML, which is a text format. So you can create the files in any text editor. An IDE with good XML support is recommended.

If there already exists a CAD model of the robot, there are some tools that can be used to convert the CAD model to URDF. Here is a non-exhaustive list:

Known Issues

2024-07-13 14:39