Tactile Sensor ROS 2 Bridge: Arduino to ROS 2 Jazzy with Python🖐️📡

This project provides a robust Python bridge to connect an Arduino-based tactile sensor to ROS 2 Jazzy. It leverages a Python node for serial communication, enabling seamless data flow from your physical sensor to your ROS 2 ecosystem.

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🚀 Getting Started

Follow these steps to set up your tactile sensor bridge.

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🔌 Step 1: Prepare the Arduino

First, you'll need to flash your Arduino with the appropriate firmware.

1. Upload the Sketch:
   • Navigate to the arduino/ directory in this repository (assuming you'll add an arduino folder containing your .ino sketch here).
   • Open the provided .ino sketch in the Arduino IDE.
   • Ensure your Arduino board and port are correctly selected.
   • Upload the sketch to your Arduino board. This sketch is responsible for reading sensor data and sending it over the serial port.

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💻 Step 2: Connect Arduino to ROS 2 in WSL (Ubuntu on Windows)

Since WSL (Windows Subsystem for Linux) does not have direct access to USB devices, we'll use usbipd to share your Arduino from Windows to WSL.

🧰 Prerequisites (Run in PowerShell as Administrator)

1. Install usbipd utility:

   winget install --interactive --exact dorssel.usbipd-win

2. List USB devices and get your Arduino's BUSID:

   usbipd wsl list

   Look for your Arduino (e.g., "Arduino Uno", "CH340", "USB-SERIAL CH340") and note its BUSID (e.g., 1-4).

3. Bind the device to make it shareable:

   usbipd bind --busid <BUSID_FROM_ABOVE>

   Replace <BUSID_FROM_ABOVE> with the actual BUSID you found.

4. Attach the device to your WSL instance:

   usbipd attach --wsl --busid <BUSID_FROM_ABOVE>

   Again, replace <BUSID_FROM_ABOVE> with your device's BUSID.

🐧 In Ubuntu (WSL)

1. Verify connection:

   ls /dev/ttyACM*

   If you see /dev/ttyACM0 (or similar, like /dev/ttyUSB0), your Arduino is successfully connected!

2. Add your user to the dialout group for serial port access:

   sudo usermod -a -G dialout $USER

   After running this, close and reopen your WSL terminal for the changes to take effect.

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📦 Step 3: Create ROS 2 Python Package

Now, let's set up your ROS 2 workspace and package.

1. Create and navigate to your ROS 2 workspace:

   mkdir -p ~/ros2_ws/src
   cd ~/ros2_ws/src

2. Create the Python package:

   ros2 pkg create --build-type ament_python --node-name tactile_publisher tactile_sensor_pkg

   This creates a package named tactile_sensor_pkg with an executable node called tactile_publisher.

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✍️ Step 4: Write the ROS 2 Node

Time to write the Python script that reads from the serial port and publishes data to ROS 2.

1. Navigate to your package's Python directory:

   cd ~/ros2_ws/src/tactile_sensor_pkg/tactile_sensor_pkg

2. Create the Python publisher script:

   nano tactile_publisher.py

   Then, paste your Python script here. This script will handle the serial communication with your Arduino and publish the sensor data to a ROS 2 topic (e.g., as std_msgs/msg/Int32 or Float32).

   To save and exit nano: Press CTRL + O, then ENTER, then CTRL + X.

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⚙️ Step 5: Configure Package Files

We need to tell ROS 2 how to find and run your new Python node, and add necessary dependencies.

1. Install python3-serial module:

   sudo apt update
   sudo apt install python3-serial

2. Update setup.py (located at ~/ros2_ws/src/tactile_sensor_pkg/setup.py): Open this file and add the entry_points dictionary. This tells ROS 2 about your executable node.

   from setuptools import find_packages, setup
   
   package_name = 'tactile_sensor_pkg'
   
   setup(
       name=package_name,
       version='0.0.0',
       packages=find_packages(exclude=['test']),
       data_files=[
           ('share/ament_index/resource_index/packages',
               ['resource/' + package_name]),
           ('share/' + package_name, ['package.xml']),
       ],
       install_requires=['setuptools'],
       zip_safe=True,
       maintainer='your_name', # <--- Update this!
       maintainer_email='your_email@example.com', # <--- Update this!
       description='ROS 2 package for tactile sensor bridge',
       license='Apache-2.0', # Or MIT, matching your LICENSE file
       tests_require=['pytest'],
       entry_points={
           'console_scripts': [
               'tactile_publisher = tactile_sensor_pkg.tactile_publisher:main',
           ],
       },
   )

3. Update package.xml (located at ~/ros2_ws/src/tactile_sensor_pkg/package.xml): Add the necessary runtime dependencies for your node.

   <?xml version="1.0"?>
   <?xml-model href="[http://download.ros.org/schema/package_format3.xsd](http://download.ros.org/schema/package_format3.xsd)" schematypens="[http://www.w3.org/2001/XMLSchema](http://www.w3.org/2001/XMLSchema)"?>
   <package format="3">
     <name>tactile_sensor_pkg</name>
     <version>0.0.0</version>
     <description>ROS 2 package for tactile sensor bridge</description>
     <maintainer email="your_email@example.com">your_name</maintainer> <license>Apache-2.0</license> <depend>rclpy</depend>
     <depend>std_msgs</depend> <depend>pyserial</depend> <test_depend>ament_copyright</test_depend>
     <test_depend>ament_flake8</test_depend>
     <test_depend>ament_pep257</test_depend>
     <test_depend>python3-pytest</test_depend>
   
     <export>
       <build_type>ament_python</build_type>
     </export>
   </package>

   Make sure to update the maintainer tags with your information.

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🔨 Step 6: Build, Source, and Run

Finally, build your ROS 2 package and run the node!

1. Navigate to the root of your workspace:

   cd ~/ros2_ws

2. Build your package:

   colcon build --packages-select tactile_sensor_pkg

   This compiles your Python package.

3. Source your workspace:

   source install/setup.bash

   This makes your new package and its nodes available to ROS 2.

4. Run your publisher node:

   ros2 run tactile_sensor_pkg tactile_publisher

   You should now see output from your node (e.g., publishing messages or serial read errors if not connected).

   To verify messages, open another terminal (and source install/setup.bash again) and run:

   ros2 topic echo /tactile_data # Adjust topic name if different

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🔁 Rebuild After Code Changes

Whenever you modify your tactile_publisher.py (or any other Python source file in the package), you need to re-source your workspace for the changes to take effect. If you modify setup.py or package.xml, you'll need to rebuild.

cd ~/ros2_ws
colcon build --packages-select tactile_sensor_pkg # Only needed if setup.py/package.xml changed
source install/setup.bash
ros2 run tactile_sensor_pkg tactile_publisher

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📁 Repository Structure

.
├── arduino/
│   └── YOUR_ARDUINO_SKETCH.ino  # Add your Arduino sketch here
├── ros2_ws/
│   ├── src/
│   │   └── tactile_sensor_pkg/
│   │       ├── tactile_sensor_pkg/
│   │       │   └── tactile_publisher.py
│   │       ├── package.xml
│   │       └── setup.py
│   ├── .gitignore              # Recommended for ROS 2 repos
│   └── README.md               # This file!
└── LICENSE                     # Your project's license file

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📌 Important Notes

• Device Access Errors: If you're running into device access errors, double-check that /dev/ttyACM0 (or ttyUSB0) is accessible and that your user is indeed in the dialout group (you must restart your WSL terminal after adding yourself).

• USB Device Disconnection: You may need to reattach the USB device using usbipd attach if it becomes disconnected (e.g., after a WSL restart or unplugging the Arduino).

• Baud Rate: Ensure the baud rate in your Arduino sketch matches the baud rate configured in your tactile_publisher.py script.

• Message Type: The example tactile_publisher.py uses std_msgs/msg/Int32. Adjust this (Float32, String, etc.) and the parsing logic in your Python script to match the data type your Arduino sends.

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✅ .gitignore for your ROS 2 Repository

Create a .gitignore file at the root of your ros2_ws/ directory to prevent unnecessary files from being tracked by Git. This keeps your repository clean and manageable.

# ROS 2 build files
build/
install/
log/

# Python cache
__pycache__/
*.pyc
*.pyo

# VSCode settings
.vscode/

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## 🧾 License

This project is licensed under the MIT License. See the LICENSE file in the root of the repository for full details.