Skip to main content

Introduction to Robotic Nervous System (ROS 2)

Introduction​

ROS 2 (Robot Operating System 2) is an open-source middleware framework that provides the communication backbone for robotics applications. Think of it as the nervous system that connects sensors, controllers, and actuators in a robot.

Learning Objectives:

  • Understand what ROS 2 is and why it's used
  • Learn the core architecture concepts
  • Install and verify ROS 2 Humble
  • Run your first ROS 2 nodes

What is ROS 2?​

ROS 2 is NOT an operating system but a middleware that runs on top of Linux (Ubuntu 22.04 recommended). It provides:

  • Communication infrastructure: Nodes talk via topics, services, and actions
  • Hardware abstraction: Same code works on different robots
  • Tools: Visualization (RViz), simulation (Gazebo), debugging
  • Packages: Reusable libraries for navigation, perception, manipulation

Key Improvements Over ROS 1​

  • Real-time support: Deterministic communication for safety-critical systems
  • Security: Encrypted and authenticated communication
  • Multi-robot: Native support for robot swarms
  • Cross-platform: Works on Linux, Windows, macOS

Core Concepts​

Nodes​

Independent processes that perform specific tasks (e.g., camera driver, path planner).

Topics​

Asynchronous publish-subscribe channels for streaming data (e.g., sensor readings).

Services​

Synchronous request-response patterns (e.g., "calculate path from A to B").

Actions​

Long-running tasks with feedback (e.g., "navigate to goal, send progress updates").

Installation (Ubuntu 22.04)​

# Add ROS 2 repository
sudo apt update && sudo apt install -y software-properties-common
sudo add-apt-repository universe
sudo apt update && sudo apt install curl -y
sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg

# Install ROS 2 Humble Desktop
sudo apt update
sudo apt install ros-humble-desktop -y

# Source ROS 2 environment
source /opt/ros/humble/setup.bash
echo "source /opt/ros/humble/setup.bash" >> ~/.bashrc

Verification​

Test your installation:

# Terminal 1: Run a talker node
ros2 run demo_nodes_cpp talker

# Terminal 2: Run a listener node
ros2 run demo_nodes_cpp listener

You should see the listener receiving messages from the talker.

ROS 2 CLI Tools​

# List running nodes
ros2 node list

# List active topics
ros2 topic list

# See topic messages
ros2 topic echo /chatter

# Get node info
ros2 node info /talker

Exercises​

  1. Install ROS 2 Humble on Ubuntu 22.04
  2. Run the talker/listener demo
  3. Use ros2 topic echo to view messages
  4. Explore available ROS 2 packages with ros2 pkg list

Summary​

ROS 2 is the communication middleware that enables modular, distributed robotics systems. It provides nodes, topics, services, and actions as building blocks for robot software.

Further Reading​