MyRoboPathOpen Robotics Lab
ros217 min readUpdated 2026-03-08Intermediate

URDF & Xacro Robot Modeling: Links, Joints, Visual & Physics

Build modular, maintainable Unified Robot Description Format (URDF) models using Xacro macros, calculate correct 3D inertial tensors, and visualize in RViz 2.

MyRoboPath Engineering Lab
Peer-Reviewed Open-Source Hardware & Firmware Guide

Key Engineering Takeaways

  • •Never write raw repetitive URDF—use Xacro macros to parameterize wheel diameters, mass properties, and colors.
  • •Separate complex visual STL/DAE meshes from simplified convex hull collision geometries (cylinders, boxes) to speed up collision checking 100x.
  • •Accurate inertial tensors (ixx, iyy, izz) are strictly mandatory for realistic physics simulation in Gazebo and MuJoCo.
Prerequisites
  • • XML syntax basics
  • • 3D coordinate systems

URDF Anatomy: Links, Joints, Visuals & Collisions

A URDF defines the kinematic tree of a robot consisting of Links (rigid bodies) connected by Joints (revolute, continuous, prismatic, fixed, floating).

Tags:#URDF#Xacro#RViz#Simulation#Inertia#Robot State Publisher