Category: Courses

ROS2 Basics (Python) – A 4-Month Self-Study Course

\\Course Description:\\ \Welcome to “ROS2 Basics (Python),” a comprehensive 4-month (approximately 16-week) self-study course designed to equip you with the fundamental knowledge and practical skills to develop robotics applications using ROS2 (Robot Operating System 2) with Python. This course is crafted for motivated beginners and intermediate learners who are eager to delve into the world of robotics programming. We’ll start from the ground up, covering essential ROS2 concepts, Python programming for robotics, and hands-on examples that bring theory to life. By the end of this course, you’ll be capable of building and running your own basic ROS2-powered robot applications.\

\\Primary Learning Objectives:\\ \Upon successful completion of this course, you will be able to:\ \ \Understand the core concepts and architecture of ROS2.\ \Develop ROS2 nodes, publishers, subscribers, services, and actions using Python.\ \Utilize ROS2 tools for introspection, debugging, and data visualization.\ \Create and manage ROS2 packages and workspaces.\ \Implement basic robot control and sensor data processing using ROS2 and Python.\ \Apply acquired knowledge to a cumulative final project involving a simulated robot.\ \

\\Necessary Materials:\\ \ \A computer running a Linux distribution (Ubuntu 20.04 LTS or newer recommended)\ \Stable internet connection for resources and software downloads\ \Text editor or Integrated Development Environment (IDE) like VS Code\ \Access to a ROS2 Foxy Fitzroy (or newer, depending on availability and system compatibility) installation\ \Familiarity with basic Linux command line operations\ \Basic Python programming knowledge\ \

Course Content: 14 Weekly Lessons

Week 1-2: Foundations of ROS2 and Python

\Lesson 1: Introduction to ROS2 and its Ecosystem\ \ \\Learning Objectives:\
\ \Understand the history and evolution from ROS1 to ROS2.\ \Identify the key advantages and motivations behind using ROS2.\ \Describe the core components of the ROS2 architecture (nodes, topics, services, actions).\ \ \ \\Key Vocabulary:\
\ \\ROS (Robot Operating System):\ A flexible framework for writing robot software.\ \\ROS2:\ The next generation of ROS, designed for more robust and secure robotics applications.\ \\Node:\ An executable process in ROS2 that performs a specific computation.\ \\Topic:\ A named bus over which nodes exchange messages.\ \\Message:\ A data structure that passes information between nodes.\ \\Service:\ A request/reply mechanism for direct communication between nodes.\ \\Action:\ A long-running, goal-oriented communication mechanism for asynchronous tasks.\ \ \ \\Content:\
\ROS (Robot Operating System) has been a cornerstone of robotics development for over a decade. ROS2 is its powerful successor, rebuilt from the ground up to address the demands of modern robotics, including real-time performance, multi-robot systems, and security.\ \At its heart, ROS2 operates on a distributed communication graph. Instead of a centralized master like in ROS1, ROS2 uses DDS (Data Distribution Service) for direct peer-to-peer communication between nodes. This enhances reliability and scalability.\ \Think of nodes as individual programs or modules that perform a specific function – perhaps one node controls a robot’s motors, while another processes camera data. These nodes communicate by sending and receiving messages over topics. For instance, a “camera\_publisher” node might publish image messages on a \/camera/image\_raw\ topic, and an “image\_processor” node would subscribe to that topic to receive the images.\ \Beyond topics, ROS2 offers services for synchronous request-reply interactions (e.g., “request the robot’s current pose” and get an immediate reply). For more complex, long-running tasks like “navigate to a specific point,” actions provide a robust, asynchronous communication pattern, allowing for goal setting, feedback, and result retrieval.\ \ \\Hands-on Example:\
\ \\Install ROS2 Foxy Fitzroy (or appropriate version):\ Follow the official ROS2 documentation for your specific Linux distribution.\ \\Source your ROS2 environment:\ \source /opt/ros/foxy/setup.bash\ (adjust for your ROS2 version).\ \\Run \ros2 daemon –help\ and \ros2 run –help\:\ Explore the command-line help for basic ROS2 commands to get a feel for the CLI tools.\ \ \ \

\Lesson 2: Setting up Your ROS2 Workspace and Basic Python\ \ \\Learning Objectives:\
\ \Understand the concept of a ROS2 workspace.\ \Learn to create and initialize a ROS2 workspace.\ \Review fundamental Python syntax relevant to ROS2 programming.\ \ \ \\Key Vocabulary:\
\ \\Workspace:\ A directory containing ROS2 packages and build artifacts.\ \\Package:\ The fundamental unit of organization in ROS2, containing source code, build files, and resources.\ \\\colcon\:\ The build tool used in ROS2.\ \\\setup.py\:\ Python setuptools file used to define Python packages.\ \\\ament\_python\:\ ROS2 build type for Python packages.\ \ \ \\Content:\
\A ROS2 workspace is where you’ll develop your own ROS2 packages. It’s essentially a directory structure that \colcon\, the ROS2 build tool, understands. By building your packages within a workspace, \colcon\ can properly find dependencies and compile your code.\ \Python is a popular choice for ROS2 development due to its readability and extensive libraries. While this course assumes basic Python knowledge, we’ll quickly recap essential concepts: variables, data types (integers, floats, strings, booleans, lists, dictionaries), control flow (if/else, for loops, while loops), functions, and basic object-oriented programming (classes and objects). These are the building blocks for writing ROS2 nodes in Python.\ \ \\Hands-on Example:\
\ \\Create a ROS2 workspace:\
\\mkdir -p \~/ros2\_ws/src
cd \~/ros2\_ws
colcon build
\\ \ \\Source the workspace:\
\\source install/setup.bash
\\ \ \\Create a simple Python script (\hello.py\):\
\\def greet(name):
return f”Hello, {name}\!”

if **name** == “**main**”:
print(greet(“ROS2 World”))
\\

\ \\Run the Python script:\ \python3 hello.py\\ \ \ \

Week 3-4: ROS2 Communication Fundamentals (Topics)

\Lesson 3: Creating Your First ROS2 Python Node: Publishers\ \ \\Learning Objectives:\
\ \Understand the role of a publisher in ROS2.\ \Create a simple ROS2 Python node that publishes messages to a topic.\ \Learn how to define and use standard ROS2 message types.\ \ \ \\Key Vocabulary:\
\ \\Publisher:\ A node that sends messages on a topic.\ \\\rclpy\:\ The ROS Client Library for Python.\ \\\Node\ class:\ The base class for all ROS2 Python nodes.\ \\\create\_publisher\:\ Method to create a publisher.\ \\\publish\:\ Method to send a message.\ \\\String\ message:\ A standard ROS2 message type for plain text.\ \ \ \\Content:\
\The most common way for ROS2 nodes to communicate is through topics, using a publish/subscribe model. A publisher node sends out messages on a specific topic, and any subscriber node interested in that data can receive them. This is an asynchronous, one-to-many communication pattern.\ \In Python, \rclpy\ is the library that enables you to interact with ROS2. To create a publisher, you’ll typically subclass the \Node\ class, initialize it, and then use the \create\_publisher\ method. This method requires the message type, the topic name, and a quality of service (QoS) profile. For simple data like text, the \String\ message type is often used. You’ll then use a