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Gazebo Basics

Gazebo is a powerful 3D robot simulation environment used with ROS 2 to design, test, and validate robotic systems in a virtual world before applying them on real hardware. It allows developers to simulate robots, sensors, physics, and environments with high accuracy.

This lesson introduces the fundamentals of Gazebo, its integration with ROS 2, and its importance in humanoid robotics and autonomous systems.

Learning Objectives​

By the end of this lesson, students will be able to:

  • Understand what Gazebo Simulator is
  • Explain why simulation is important in robotics
  • Identify the main components of Gazebo
  • Understand worlds, models, and physics engines
  • Launch Gazebo with ROS 2 integration
  • Spawn robots into the simulation
  • Control robot movement using ROS 2 topics
  • Apply Gazebo in humanoid robotics & AI systems

Prerequisites​

  • Completed Week 1-3: ROS 2 fundamentals and architecture
  • Completed Week 4: ROS 2 Nodes & Topics
  • ROS 2 Humble installed and configured
  • Basic understanding of 3D coordinate systems and physics
  • Linux or Windows with WSL2 for Gazebo installation
  • Python 3.8+ and C++ compiler
  • Familiarity with terminal/command line operations

1. What is Gazebo?​

Gazebo is an open-source robotics simulator that provides:

  • Realistic physics engine
  • High-quality 3D graphics
  • Sensor simulation
  • Real-time control using ROS 2

It allows you to:

  • Test robot behavior safely
  • Avoid damaging real hardware
  • Debug robot software
  • Train AI models in simulation

✅ Gazebo is widely used in:

  • Humanoid robotics
  • Autonomous vehicles
  • Drones
  • Industrial robots
  • AI-based robotic training

2. Why Simulation is Important in Robotics?​

Simulation is used because:

  • ⚠️ Real robots are expensive
  • 🔧 Hardware can be damaged
  • 🧠 AI models need thousands of tests
  • 🛑 Real-world testing is risky
  • ⏱️ Simulation is faster than real time

✅ You can fail safely in Gazebo without any risk.

3. Main Components of Gazebo​

1. World​

A world is the environment where the robot exists.

It contains:

  • Ground
  • Gravity
  • Light
  • Objects
  • Obstacles

Example:

  • Office environment
  • Factory floor
  • Outdoor terrain

2. Models​

A model is any object in Gazebo:

  • Robot
  • Table
  • Box
  • Wall
  • Sensor module

Each model is built using:

  • SDF (Simulation Description Format)
  • URDF (Unified Robot Description Format)

3. Physics Engine​

Gazebo supports different physics engines:

  • ODE (default)
  • Bullet
  • DART
  • Simbody

These engines handle:

  • Gravity
  • Friction
  • Collisions
  • Force & torque

4. Sensors in Gazebo​

Gazebo can simulate:

  • Camera
  • IMU
  • Lidar
  • Force sensors
  • 🔊 Microphones

These sensors publish data as ROS 2 topics.

5. Plugins​

Plugins allow Gazebo to:

  • Control robot movement
  • Add sensors
  • Interface with ROS 2
  • Simulate motors & controllers

4. Gazebo + ROS 2 Integration​

Gazebo integrates with ROS 2 using ROS-Gazebo bridge packages.

This allows:

  • ROS 2 nodes → Control Gazebo robot
  • Gazebo sensors → Publish ROS 2 topics
  • ROS 2 algorithms → Work on simulated robot

✅ You can run the same code on simulation and real robot.

5. Launching Gazebo with ROS 2​

gazebo