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Realistic simulation environments are essential for training and evaluating embodied AI agents before deployment on physical hardware. This section introduces Gazebo Sim, the standard open-source simulator for ROS 2 robotics, with a focus on authoring rich indoor environments and using large language models to generate simulation assets from natural language descriptions. The running example throughout is the TurtleBot3 behavior demos project: a ROS 2 Jazzy robot navigating AWS RoboMaker environments using Nav2, behavior trees, and AI-based perception.

Gazebo worlds and SDF/Xacro

World file anatomy, the SDF + Xacro format, and a walkthrough of the AWS RoboMaker Small House — 68 residential furniture and appliance models.

LLM-driven world authoring

Using large language models to generate SDF/Xacro world files and Gazebo models from natural language descriptions. Prompt patterns, iterative refinement, and literature review.

Why simulation matters

Training and evaluating embodied AI agents in simulation offers several key advantages:
  • Safety — no risk of hardware damage during early exploration
  • Scale — run hundreds of parallel environments that would be impossible to instrument physically
  • Reproducibility — fixed random seeds and deterministic physics for fair comparison
  • Domain diversity — vary lighting, furniture layout, object placement, and sensor noise programmatically
The central challenge is the sim-to-real gap: models that work well in simulation often degrade when deployed on physical hardware. High-fidelity asset authoring — realistic geometry, physics, and sensor responses — closes this gap.

Simulation stack

The tutorials use the following stack:
ComponentRole
Gazebo Sim (Harmonic)Physics simulation and 3D visualization
ROS 2 JazzyRobot middleware — topics, services, actions
Nav2Autonomous navigation stack
AWS RoboMaker worldsOpen-source indoor environment assets
Docker ComposeReproducible multi-container setup