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Module 2: The Digital Twin (Gazebo & Unity)

Introduction​

Welcome to Module 2 of the Physical AI & Humanoid Robotics Textbook. In this module, we'll explore the concept of digital twins and how physics-based simulation enables the development of humanoid robots using Gazebo and Unity.

Learning Objectives​

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

  • Explain the role of digital twins in Physical AI
  • Understand basic physics simulation concepts (gravity, collisions, dynamics)
  • Describe how Gazebo simulates robots and environments
  • Understand Unity's role in high-fidelity visualization and interaction
  • Conceptually understand sensor simulation (LiDAR, depth cameras, IMUs)

Module Structure​

This module consists of four chapters that build upon each other:

  1. Digital Twins and Simulation in Physical AI - Foundational concepts
  2. Physics Simulation with Gazebo - Understanding physics simulation
  3. High-Fidelity Environments with Unity - Visualization and interaction
  4. Simulated Sensors for Humanoid Robots - Sensor simulation concepts

Prerequisites​

Before starting this module, you should have completed Module 1 and have a solid understanding of:

  • ROS 2 fundamentals
  • Robot structure and URDF concepts

Next Steps​

This module transitions learners from abstract robot structure (Module 1) to embodied behavior in simulated physical environments, preparing you for Module 3 on perception and AI.