ROS 2 Asterics Bridge

This repository provides a simple HTTP-to-ROS 2 bridge that enables accessible and symbolic explainability for robots using Asterics Grid and ROS 2.

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📚 Table of Contents

• 🧠 Purpose
• 🚀 How It Works
• 🔧 Setup Instructions
• 📤 Example Payload from Asterics Grid
• 📡 ROS 2 Topic
• 🧩 Use Case Example
• 🧱 Files
• 📜 License
• 📖 Citation
• 🤝 Acknowledgments
• 🤝 Project Acknowledgments

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🧠 Purpose

The goal of this bridge is to facilitate inclusive human–robot interaction (HRI) by enabling users to send symbolic commands or explanation requests to a robot through a pictogram-based interface (e.g. ARASAAC boards). The system is designed with Universal Design for Learning (UDL) in mind.

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🚀 How It Works

1. Asterics Grid sends HTTP POST requests with a payload (e.g. "turn", "why").
2. A lightweight Flask server receives these requests.
3. The message is published to a ROS 2 topic (/asterics_commands).
4. Robot nodes subscribed to the topic respond (e.g., by generating a verbal explanation).

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🔧 Setup Instructions

1. Install dependencies

git clone https://github.com/fjrodl/AsTeRICS-Grid

pip install flask flask-cors

2. Source your ROS 2 environment

source /opt/ros/humble/setup.bash  # or your ROS 2 distro

3. Run the bridge

python3 ros2_asterics_bridge.py

The server will listen on http://localhost:5000/command.

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📤 Example Payload from Asterics Grid

Each pictogram on the Asterics board should be configured with a custom HTTP action:

{
  "type": "HTTP",
  "method": "POST",
  "url": "http://localhost:5000/command",
  "headers": { "Content-Type": "application/json" },
  "body": {
    "payload": "turn"
  }
}

Testing the server with Curl:

curl -X POST http://localhost:5000/command      -H "Content-Type: application/json"      -d '{"payload": "turn"}'

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📡 ROS 2 Topic

The bridge publishes all incoming payloads to:

/asterics_commands  [std_msgs/msg/String]

Example message:

data: "turn"

You can test it with:

ros2 topic echo /asterics_commands

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🧩 Use Case Example

Asterics Grid	HTTP POST →	ROS 2 Topic	Robot Explanation
Pictogram: "Why?"	payload: "why"	/asterics_commands	"Because I detected an obstacle."
Pictogram: "Turn"	payload: "turn"	/asterics_commands	"Turning left to avoid object."

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🧱 Files

• ros2_asterics_bridge.py – Main Flask+ROS 2 server
• example.grd (optional) – Demo board with pictograms and HTTP actions
• guia_asterics_ros2.pdf – Setup guide (included in paper)

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📜 License

This repository (astericsgrid_ros) is distributed under the Apache License 2.0.
It is an independent bridge that connects AsTeRICS-Grid with ROS 2 via HTTP requests.

⚖️ Legal Note

• No source code from AsTeRICS-Grid is included or modified in this repository.
• This bridge only communicates externally with AsTeRICS-Grid through HTTP and does not constitute a derivative work under the AGPL v3 license.
• Users must comply with the AGPL v3 terms only when running or modifying AsTeRICS-Grid itself.

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📖 Citation

If you use this work, please cite:

Rodríguez Lera, F. J., Fernández Hernández, R., Lopez González, S., González-Santamarta, M. A., Rodríguez Sedano, F. J., & Fernandez Llamas, C. (2025). Accessible and Pedagogically-Grounded Explainability for Human-Robot Interaction: A Framework Based on UDL and Symbolic Interfaces. arXiv:2504.06189. https://arxiv.org/abs/2504.06189

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🤝 Acknowledgments

Developed as part of research on accessible explainability and Universal Design for Learning in HRI. Integrates:

• Asterics Grid
• ARASAAC pictograms
• ROS 2

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🤝 Project Acknowledgments

DMARCE (EDMAR+CASCAR) Project: EDMAR PID2021-126592OB-C21 -- CASCAR PID2021-126592OB-C22 funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe

Erasmus+ Project ROBOSTEAMSEN - Training SEN teachers to use robotics for fostering STEAM and develop computational thinking with reference: 2023-I-ESOI-KA220-SCH-OOOI55379.