Software & Middleware

URDF (Unified Robot Description Format)

URDF (Unified Robot Description Format) is an XML format from the ROS ecosystem for describing a robot's kinematic tree, specifying links with their inertial, visual, and collision properties and the joints connecting them. It is consumed by visualization, kinematics, motion planning, and simulation tools, commonly generated via xacro macros. Its tree-only topology cannot express closed kinematic chains, a limitation addressed by successors and alternatives such as SDF and MJCF.

Why it matters for physical AI

A robot's URDF is its identity card across simulators, planners, and learning frameworks, and accurate descriptions, especially inertial parameters, are quietly critical to sim-to-real transfer of learned controllers.