🤖 ROS2-Learning — ROS 2 Jazzy

A hands-on learning repository for ROS 2 Jazzy. This repository contains the exercises and projects I am building while learning ROS 2 using Python and C++.

The goal is to understand the fundamentals of ROS 2 through practical examples before moving on to larger robotics projects.

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Concepts Covered

Concept	Example	Language
Nodes	my_first_node	Python / C++
Publisher	robot_news_station	Python
Subscriber	smartphone	Python
Custom Messages	HardwareStatus.msg	ROS 2 Interface
Service Server	battery_node	Python
Service Client	battery_client	Python
Parameters	yaml_params/robot_params.yaml	Python
Launch / Bringup	my_robot_bringup	Python
Custom Interfaces	my_robot_interfaces	ROS 2 Interface
TurtleSim Project	turtlesim_catch_them_all	Python

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TurtleSim — Catch Them All

One of the main projects in this repository is a TurtleSim project where turtle1 automatically moves toward randomly spawned turtles and catches them.

How it works

• A spawner node creates turtles at random positions.
• The spawner keeps track of the active turtles.
• Turtle information is published using a custom ROS 2 message.
• The controller node receives the turtle positions.
• The controller calculates the distance and angle to the target.
• turtle1 is controlled using geometry_msgs/Twist.
• When the target is reached, a custom CatchTurtle service removes the turtle.
• ROS 2 parameters are used to control the spawn frequency, turtle name prefix, and target selection.

Nodes

turtle_spawner
      │
      │ alive_turtles
      ▼
turtle_controller
      │
      │ /turtle1/cmd_vel
      ▼
    turtle1

🛠️ Setup

Prerequisites

• Ubuntu 24.04
• ROS 2 Jazzy
• Python 3
• colcon
• turtlesim

Clone the Repository

git clone https://github.com/sujan-coder/ROS2-Learning.git
cd ROS2-Learning

Build the Workspace

source /opt/ros/jazzy/setup.bash
colcon build
source install/setup.bash

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Run TurtleSim Project

1. Start TurtleSim

Open a terminal and run:

ros2 run turtlesim turtlesim_node

2. Start the Turtle Spawner

Open another terminal:

source install/setup.bash
ros2 run turtlesim_catch_them_all spawner

3. Start the Controller

Open a third terminal:

source install/setup.bash
ros2 run turtlesim_catch_them_all controller

The spawner will create turtles at random positions, and the controller will automatically move turtle1 toward them and catch them.

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Repository Structure

ROS2-Learning/
│
├── src/
│   ├── esp_interface/
│   ├── my_cpp_pkg/
│   ├── my_py_pkg/
│   ├── my_robot_bringup/
│   ├── my_robot_interfaces/
│   │
│   └── turtlesim_catch_them_all/
│       ├── package.xml
│       ├── setup.py
│       └── turtlesim_catch_them_all/
│           ├── turtle_controller.py
│           └── turtle_spawner.py
│
├── yaml_params/
├── LICENSE
└── README.md

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Tools & Technologies

• ROS 2 Jazzy
• Ubuntu 24.04
• Python
• C++
• rclpy
• colcon
• TurtleSim
• ROS 2 Nodes
• Publishers & Subscribers
• Services
• Parameters
• Custom Messages & Services

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Learning Progress

This repository is a work in progress.

I am using it to learn ROS 2 by building small working examples and gradually applying the concepts to more complex projects.

Currently Learning

• ROS 2 Nodes
• Topics
• Publishers & Subscribers
• Services
• Custom Interfaces
• Parameters
• Launch files
• Robot bringup
• Hardware interfaces

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Note:

This repository is part of my personal ROS 2 learning journey. Some examples are based on coursework, while others are modified as I learn and experiment.