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Chapter 6: Gazebo Simulation for Humanoid Robots

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Fill in content from specs/001-physical-ai-book-specs/spec.md lines 608-693. Use Chapter 5 (05-simulation-foundations.mdx) as formatting reference.

Overview​

TODO: Add overview paragraph introducing Gazebo as the industry-standard ROS 2 simulator (spec.md lines 610-612)

Target Audience: Developers ready to simulate ROS 2 robots in Gazebo.

Learning Objectives​

By the end of this chapter, you will be able to:

  1. TODO: Add learning objective 1 from spec.md line 616
  2. TODO: Add learning objective 2 from spec.md line 617
  3. TODO: Add learning objective 3 from spec.md line 618
  4. TODO: Add learning objective 4 from spec.md line 619
  5. TODO: Add learning objective 5 from spec.md line 620
  6. TODO: Add learning objective 6 from spec.md line 621

Gazebo Architecture: Server vs. Client​

TODO: Explain Gazebo architecture (spec.md lines 625-626)

  • Server: Physics simulation
  • Client: Visualization
  • How they communicate

SDF vs. URDF: Choosing the Right Format​

TODO: Explain when to use SDF vs. URDF (spec.md line 626)

  • URDF: Robot descriptions (with Gazebo extensions)
  • SDF: World files and standalone models

Installing Gazebo on Ubuntu 22.04​

TODO: Add installation instructions and verification steps (spec.md lines 640-663)

# TODO: Add commands from spec.md lines 642-663
# - Install Gazebo Harmonic
# - Launch Gazebo
# - Spawn robot using gazebo_ros
# - Launch with custom world
# - List models
# - Check version
# - Launch ROS 2 + Gazebo integration

Creating Custom Simulation Worlds​

TODO: Add section on creating world files (spec.md lines 628, 635)

  • Ground plane
  • Lighting
  • Obstacles
  • Gravity and physics parameters

Example World File:

<!-- TODO: Add example world file from spec.md line 635 -->

Spawning Humanoid Robots in Gazebo​

TODO: Explain spawning process (spec.md lines 629, 637)

  • Publishing URDF to /robot_description
  • Using ros2 run gazebo_ros spawn_entity.py

Example Launch File:

# TODO: Add launch file example from spec.md line 637

Gazebo Plugins for Sensors and Actuators​

TODO: Explain Gazebo plugins (spec.md lines 627, 630-631)

Camera Plugin​

TODO: Add camera plugin example (spec.md line 638)

<!-- TODO: Add camera plugin configuration -->

LiDAR Plugin​

TODO: Add LiDAR plugin example

IMU Plugin​

TODO: Add IMU plugin example

Integrating Gazebo with ROS 2​

TODO: Explain gazebo_ros_pkgs and ROS 2 bridge (spec.md line 631)

Mermaid Diagram TODO: Create Gazebo + ROS 2 Architecture diagram (spec.md line 667)

TODO: Show Gazebo Server → Gazebo Plugins → ROS 2 Topics → RViz

Visualizing Sensor Data in RViz​

TODO: Add section on using RViz alongside Gazebo (spec.md line 620)

  • Launching RViz
  • Configuring displays for camera, LiDAR
  • Synchronizing TF frames

Debugging Common Gazebo Issues​

TODO: Add troubleshooting section (spec.md line 621)

  • Model not spawning
  • Sensor data not publishing
  • Physics instability
  • Plugin errors

Practice Tasks​

Complete these exercises to master Gazebo simulation:

Task 1: Install Gazebo​

TODO: Add task details from spec.md line 674

Task 2: Create Custom World​

TODO: Add task details from spec.md line 675

Task 3: Spawn URDF Robot​

TODO: Add task details from spec.md line 676

Task 4: Add Camera Plugin​

TODO: Add task details from spec.md line 677

Summary​

TODO: Add summary points from spec.md lines 680-686:

  • Gazebo as 3D simulator with physics and ROS 2 integration
  • SDF for worlds, URDF for robots
  • Gazebo plugins for sensors and communication
  • gazebo_ros_pkgs for ROS 2 integration
  • Spawning process
  • Sensor data flow through ROS 2 topics

References​

Next Chapter: Chapter 7: Unity for Humanoid Robot Visualization - Learn how to use Unity for photorealistic rendering and visualization.