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Module 2: The Digital Twin (Gazebo & Unity)

Master physics simulation and visualization for robot development

Module Overview​

This module teaches you to create digital twins—virtual representations of physical robots. You'll learn Gazebo for physics simulation and Unity for high-quality visualization, enabling you to develop and test robots without physical hardware.

By the end of this module, you will:

  • Understand digital twin concepts and benefits
  • Set up Gazebo simulation environments
  • Spawn and control robots in Gazebo
  • Integrate sensors (cameras, LiDAR, IMU) in simulation
  • Use Unity for photorealistic visualization
  • Build human-robot interaction scenes

Prerequisites​

  • Module 1 Complete: ROS 2 fundamentals and URDF modeling
  • Ubuntu 22.04: With ROS 2 Humble/Iron installed
  • Gazebo: Installed via ROS 2 packages
  • Unity (Optional): For visualization chapters

Module Structure​

Chapter 1: Gazebo Simulation Basics​

Type: Theory-to-Practice
Lessons: 6
Duration: 10-12 hours

You will learn:

  • Gazebo's role in robotics development
  • Setting up simulation environments
  • Spawning robots from URDF/SDF
  • Physics engines and simulation parameters
  • Sensor simulation (cameras, LiDAR, IMU)
  • Visualization and debugging tools

→ Start Chapter 1

Chapter 2: Robot Control in Gazebo​

Type: Practice-Heavy
Lessons: 6
Duration: 12-14 hours

You will learn:

  • Controlling robot joints via ROS 2 topics
  • ros2_control for hardware abstraction
  • Position, velocity, and effort control modes
  • Mobile base control (differential drive)
  • Manipulator arm control
  • Trajectory execution

→ Start Chapter 2

Chapter 3: Unity Integration for Visualization​

Type: Practice-Heavy
Lessons: 4
Duration: 8-10 hours

You will learn:

  • Unity's role in robotics visualization
  • ROS-TCP-Connector setup
  • Basic robot visualization in Unity
  • Sensor data streaming from ROS 2
  • Human-robot interaction scenes

→ Start Chapter 3

Module Learning Path​

Chapter 1: Gazebo Basics
    ↓ (Understand simulation fundamentals)
Chapter 2: Robot Control
    ↓ (Control robots in simulation)
Chapter 3: Unity Visualization
    ↓ (High-quality visualization)
───────────────────────────────────
Module 2 Complete! → Module 3: AI-Robot Brain

Estimated Time Commitment​

ComponentTime
Reading & Theory10-12 hours
Hands-On Practice20-26 hours
Projects8-12 hours
Total Module 238-50 hours

Recommended Pace: 10-15 hours per week = 3-4 weeks to complete

What You'll Build​

Chapter 1 Projects​

  • Spawn simple robot in Gazebo
  • Add sensors (camera, LiDAR, IMU)
  • Tune physics parameters

Chapter 2 Projects​

  • Control joints via ROS 2 topics
  • Set up ros2_control
  • Control mobile base navigation
  • Control manipulator arm

Chapter 3 Projects​

  • Unity robot visualization
  • Sensor data streaming
  • Human-robot interaction scene

Success Criteria​

You have successfully completed Module 2 when you can:

  • Spawn robots in Gazebo from URDF/SDF
  • Simulate sensors and access data via ROS 2
  • Control robots using ros2_control
  • Visualize robots in Unity
  • Create basic human-robot interaction scenes

Tools & Resources​

Required Software​

  • Gazebo: Classic (ROS 2 Humble) or Garden (ROS 2 Iron)
  • ROS 2: Humble or Iron
  • Unity (Optional): 2021.3 LTS or newer
  • ROS-TCP-Connector: For Unity integration

Installation Guides​

Reference Documentation​

Ready to Begin?​

Start with Chapter 1: Gazebo Simulation Basics

Learn to create and control robots in simulation.

Start Chapter 1 →