HALO: Language-Conditioned Overhead Monocular Aerial Exploration and Navigation

IEEE Robotics and Automation Letters (RA-L), 2026

Yuezhan Tao* · Dexter Ong* · Fernando Cladera · Jason Hughes · Camillo J. Taylor · Pratik Chaudhari · Vijay Kumar

* Equal contribution

📄 Paper | 🎥 Video | 🌐 Project Page

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Overview

HALO is a language-conditioned autonomous aerial exploration and navigation system designed for overhead monocular UAV operation. The system enables a robot to explore unknown environments, build semantic maps, and search for user-specified targets using natural language prompts.

This repository provides the official release, including simulation tools, ROS integration, configuration files, and deployment utilities.

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Repository Contents

This release includes:

• Source code
• ROS launch files
• Configuration files
• Utility scripts
• tmux session scripts for simulation and robot deployment
• Dockerfiles
• Unity simulation binaries

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System Requirements

This repository has been tested with:

• Ubuntu 22.04
• ROS 2 Humble

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Quick Start for Simulation

We provide Docker scripts for a quick simulation setup.

1. Build the Docker Image

./build_sim.sh

2. Start the Docker Container

./run_sim.sh

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Simulation Binary

Please download the Unity simulation binaries from the following link:

HALO Binary

After downloading, unzip the binaries and copy them into the Docker container:

docker cp aerial_sim_binaries/ air_sem_exp:/root/ros2_ws/src/

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Running the Simulation with ROS

The provided tmux script launches the full simulation stack using tmuxp.

cd ros2_ws/src/air_sem_explorer/tmux
tmuxp load sim.yaml

This launches:

• Zenoh router
• Unity simulator
• Planner node
• Geometric mapper node
• Semantic mapper node
• Simulation tracker node

To trigger exploration, go to the Trigger tmux tab and press Enter.

To shut down all processes, go to the final kill tmux tab and press Enter.

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Configuration

Change the Map Boundary

Edit:

air_sem_explorer/config/map_common.yaml

Change the Default Task Prompt or Retask the Robot

Edit:

air_sem_gridmap/config/config.yaml

Use:

ros2 service call /set_prompt air_sem_gridmap_interfaces/srv/SetPrompt "{prompt: '<prompt1,prompt2>'}"

When using the tmux script, a GUI window will also appear to allow you to set the task prompt.

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Acknowledgements

We thank the authors of the following repositories for their open-source code:

• RayFronts
• RADIO
• VGGT
• VGGT-SLAM

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Citation

If you find our paper or code useful, please consider citing:

@article{tao2025halo,
  title={HALO: High-Altitude Language-Conditioned Monocular Aerial Exploration and Navigation},
  author={Tao, Yuezhan and Ong, Dexter and Cladera, Fernando and Hughes, Jason and Taylor, Camillo J and Chaudhari, Pratik and Kumar, Vijay},
  journal={arXiv preprint arXiv:2511.17497},
  year={2025}
}