Autonomous Explorer Node for Frontier Exploration

This repository contains a ROS 2 package implementing an autonomous frontier exploration algorithm using Nav2. The Explorer Node subscribes to a map, detects frontiers, and sends navigation goals to explore the environment.

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WhatsApp-Video-2025-05-21-at-000.mp4

Features

• Frontier Detection: Automatically detects frontiers (unknown areas) in the map.
• Autonomous Navigation: Uses Nav2's NavigateToPose action to navigate to frontiers.
• Dynamic Goal Selection: Chooses the closest unexplored frontier for efficient exploration.
• ROS 2-Based: Compatible with ROS 2 (tested on Humble or Foxy distribution).
• Customizable Timer: Adjust the exploration frequency as needed.

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Requirements

• ROS 2 (Humble/Foxy)
• Python 3
• TurtleBot3 packages installed
• Nav2 installed and configured for your robot
• SLAM Toolbox installed
• numpy Python library

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Setup

1. Clone the repository into your ROS 2 workspace:

   cd ~/ros2_ws/src
   git clone https://github.com/AniArka/Autonomous-Explorer-and-Mapper-ros2-nav2.git
   cd ~/ros2_ws
   colcon build

2. Install dependencies:

   pip install numpy

3. Source the workspace:

   source ~/ros2_ws/install/setup.bash

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Testing with TurtleBot3

Follow these steps to test the Explorer Node with TurtleBot3 in a Gazebo simulation:

1. Launch the TurtleBot3 world in Gazebo:

   ros2 launch turtlebot3_gazebo turtlebot3_world.launch.py

2. Start the Nav2 stack:

   ros2 launch nav2_bringup navigation_launch.py use_sim_time:=True

3. Launch SLAM Toolbox for mapping:

   ros2 launch slam_toolbox online_async_launch.py

4. Launch RViz for visualization:

   ros2 launch nav2_bringup rviz_launch.py

5. Run the Explorer Node:

   ros2 run custom_explorer explorer

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How It Works

1. Map Subscription: Subscribes to the /map topic to receive occupancy grid maps.
2. Frontier Detection: Identifies free cells adjacent to unknown areas as frontiers.
3. Navigation: Sends goals to Nav2's NavigateToPose action server for autonomous navigation to the closest frontier.
4. Dynamic Goal Selection: Continuously updates and selects frontiers during exploration.

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Code Structure

• explorer.py: Main node for detecting frontiers and sending navigation goals.
• requirements.txt: Python dependencies.
• README.md: Project documentation.

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Example Workflow

1. Start the TurtleBot3 simulation environment.
2. Run the Explorer Node as shown in the "Testing with TurtleBot3" section.
3. Visualize progress in RViz as the robot autonomously explores the environment.

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Future Improvements

• Add support for multi-robot exploration.
• Implement a more advanced frontier selection algorithm.
• Optimize for larger environments.

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Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

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Acknowledgments

• ROS 2 Documentation
• Nav2
• SLAM Toolbox
• TurtleBot3