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Simulation

AirStack provides high-fidelity simulation environments for developing and testing autonomous systems before deploying to hardware. Simulation enables rapid iteration, safe testing of edge cases, and multi-robot scenarios.

Directory Structure

The simulation components are organized under simulation/:

simulation/
├── isaac-sim/
│   ├── docker/                    # Isaac Sim containerization
│   │   ├── docker-compose.yaml    # Main launch configuration
│   │   └── Dockerfile.isaac-ros   # Image definition
│   ├── assets/                    # 3D models and props
│   ├── config/                    # Simulation configurations
│   ├── extensions/                # Custom Isaac Sim extensions
│   ├── launch_scripts/            # Python launch scripts
│   └── standalone_examples/       # Example scenes and scripts
└── simple-sim/
    ├── docker/                    # Simple simulator container
    │   └── docker-compose.yaml    # Launch configuration
    ├── models/                    # Lightweight simulation models
    └── ros_ws/                    # Simple sim ROS workspace

Launch Structure

Simulation components are launched via Docker Compose. Each simulator has its own configuration:

  • Isaac Sim: simulation/isaac-sim/docker/docker-compose.yaml
  • Simple Sim: simulation/simple-sim/docker/docker-compose.yaml

Key launch points:

  • Launch command: airstack up isaac-sim or airstack up simple-sim
  • Main process: The command: in docker-compose.yaml starts the simulator
  • Scene selection: Set via ISAAC_SIM_SCENE environment variable (Isaac Sim)
  • Auto-launch: Controlled by PLAY_SIM_ON_START variable

Example: 

# Launch Isaac Sim with custom scene
ISAAC_SIM_SCENE=scenes/custom_scene.usd airstack up isaac-sim

# Launch simple simulator
airstack up simple-sim

Learn more: Docker Workflow

Simulation Platforms

NVIDIA Isaac Sim (Primary)

Isaac Sim is our primary simulation platform, offering:

  • Photorealistic rendering with ray-traced graphics
  • Accurate physics simulation via NVIDIA PhysX
  • ROS 2 integration through Pegasus extension
  • Multi-robot support with independent namespaces
  • Sensor simulation (cameras, depth, IMU, GPS, LiDAR)
  • Custom scene creation with USD format

Getting Started:

Simple Sim (Lightweight)

A lightweight 2D/3D simulator for basic testing and development when full Isaac Sim fidelity isn't needed.

Use cases:

  • Quick algorithm prototyping
  • CI/CD testing
  • Lower hardware requirements
  • Faster iteration cycles

Launch: airstack up simple-sim

Location: simulation/simple-sim/

Common Workflows

Single Robot Simulation

  1. Launch the full stack: 

    airstack up

  2. Isaac Sim starts with the configured scene

  3. Robot autonomy stack connects and begins operation
  4. Monitor via Ground Control Station

See: Getting Started

Multi-Robot Simulation

  1. Launch multiple robots: 

    NUM_ROBOTS=3 airstack up

  2. Each robot gets independent ROS 2 namespace

  3. All robots visible in same Isaac Sim scene
  4. Coordinate via ground control station

Learn more: Docker Workflow

Custom Scenes

Create custom Isaac Sim scenes with:

  • Custom environments (buildings, forests, urban)
  • Multiple robots
  • Specific sensor configurations
  • Dynamic obstacles

See: Pegasus Scene Setup

Configuration

Key environment variables for simulation (set in .env or at runtime):

Variable Description Default
ISAAC_SIM_SCENE Path to USD scene file simulation/isaac-sim/scenes/...
PLAY_SIM_ON_START Auto-start simulation true
NUM_ROBOTS Number of robots to spawn 1

Example: 

# Custom scene
ISAAC_SIM_SCENE=scenes/custom.usd airstack up isaac-sim

# Don't auto-play
PLAY_SIM_ON_START=false airstack up isaac-sim

Pre-built scenes: Located in scenes/ directory

  • two_drone_fire_new.usd - Fire academy scenario
  • two_drone_RetroNeighborhood.usd - Urban neighborhood

Learn more: Docker Workflow

Troubleshooting

Isaac Sim won't start:

  • Check GPU requirements (RTX 3070+ recommended)
  • Verify NVIDIA Container Toolkit installation
  • Check disk space (25GB+ free required)

ROS 2 communication issues:

  • Verify all containers on same Docker network (docker network ls)
  • Check ROS_DOMAIN_ID settings in containers
  • See Docker Workflow

Performance issues:

  • Reduce scene complexity
  • Lower rendering quality in Isaac Sim settings
  • Close unnecessary applications
  • Use simple-sim for lighter workloads

Next Steps