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# Module 2: Gazebo & Unity - The Digital Twin

This module focuses on simulation environments that serve as "digital twins" for physical robots. Simulation is a critical component of robotics development, allowing for safe, cost-effective testing and development before deployment on physical hardware.

## Learning Objectives

By the end of this module, you will be able to:
- Understand physics simulation concepts and their importance in robotics
- Build and configure simulation environments in Gazebo
- Implement sensor simulation for cameras, LIDAR, IMUs, and other robot sensors
- Create high-fidelity rendering and visualization using Unity
- Design human-robot interaction scenarios in simulation
- Integrate Gazebo and Unity for comprehensive simulation workflows

## Module Structure

This module contains 4 chapters that will progressively build your understanding of simulation:

1. [Chapter 1: Physics Simulation Basics](./chapter1.md) - Fundamentals of physics simulation
2. [Chapter 2: Sensors and Environment Building](./chapter2.md) - Creating sensor models and environments
3. [Chapter 3: High-Fidelity Rendering & Human-Robot Interaction](./chapter3.md) - Visualization and interaction
4. [Chapter 4: Integrating Gazebo and Unity](./chapter4.md) - Combining simulation platforms

## Why Simulation Matters

Simulation plays a crucial role in humanoid robotics development:

- **Safety**: Test complex behaviors without risk of damaging expensive hardware
- **Cost-effectiveness**: Experiment with different scenarios without physical deployment
- **Repeatability**: Consistent environments for algorithm testing and debugging
- **Speed**: Accelerate development by running simulations faster than real time
- **Synthetic Data**: Generate training data for AI systems

## Prerequisites for This Module

- Basic understanding of physics concepts (motion, forces, collisions)
- Completion of Module 1 (ROS 2 concepts)
- Familiarity with 3D graphics concepts helpful but not required

## Getting Started

Begin with [Chapter 1: Physics Simulation Basics](./chapter1.md) to explore the fundamentals of physics simulation in robotics.