URDF (Unified Robot Description Format)

URDF is an XML-based file format that describes a robot's kinematic and dynamic properties: links (rigid bodies with mass, inertia, and visual/collision meshes) and joints (the connections between links, with type, axis, limits, and damping parameters). URDF is the standard robot description format in ROS and is supported by all major simulation platforms (Isaac Sim, MuJoCo, Gazebo, PyBullet). It enables loading the robot's kinematics into motion planners like MoveIt, visualizing the robot in RViz, and instantiating physics simulation models. XACRO (XML macro language) is commonly used to parameterize and modularize URDF files for complex robots. OpenArm and most SVRC hardware have publicly available URDF models.