🤖 diff_drive_bot – ROS 2 Differential Drive Simulation

This ROS 2 package simulates a differential drive robot. It processes velocity commands, converts them into wheel encoder ticks, computes odometry, publishes TF transforms, and visualizes the robot’s path using RViz.

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📁 Package Contents

File	Purpose
diff_tf.py	Computes odometry and publishes /odom and /tf using encoder ticks
twist_to_wheels.py	Converts velocity commands (/cmd_vel) into left/right encoder ticks
drive_cmd.py	Publishes sample velocity commands using geometry_msgs/Twist
drive_wheels.py	Subscribes to /cmd_vel and publishes to /lwheel and /rwheel
trajectory_publisher.py	Publishes path traced from odometry to /robot_path
__init__.py	Required Python init file for the package

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🧩 ROS 2 Topics Used

• /cmd_vel – Velocity commands (geometry_msgs/Twist)
• /lwheel & /rwheel – Wheel encoder ticks (std_msgs/Int64)
• /odom – Odometry output (nav_msgs/Odometry)
• /tf & /tf_static – Robot transform frames
• /robot_path – Path generated from odometry (nav_msgs/Path)

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⚙️ How to Run

Make sure your ROS 2 workspace is sourced and the package is built.

cd ~/ros2_ws
colcon build
source install/setup.bash

Step-by-step Execution

1. Send velocity commands:

   ros2 run diff_drive_bot drive_cmd

2. Convert cmd_vel to wheel encoder ticks:

   ros2 run diff_drive_bot twist_to_wheels

3. Compute odometry from encoder data:

   ros2 run diff_drive_bot diff_tf

4. Publish robot path:

   ros2 run diff_drive_bot trajectory_publisher

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🧰 Requirements

• ROS 2 (Foxy, Humble, or later)
• Python 3
• readchar Python module (for keyboard input in drive_cmd.py)

Install readchar if needed:

pip3 install readchar

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📚 Tutorials

Full tutorial with URDF modeling and RViz visualization:
🔗 https://github.com/JAnthem9606/ROS-Basics

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👨‍💻 Author

Developed by Bilal Ahmed (JAnthem9606)
A complete educational ROS 2 robot simulation package.

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📸 Visualization

Launch your URDF in RViz and view real-time TFs and robot path with:

ros2 launch urdf_tutorial display.launch.py model:=urdf/robot.urdf
ros2 run tf2_tools view_frames