ROS2

ROS2 (Robot Operating System 2) is the modern evolution of the original ROS project, designed for real-time, multi-robot systems with a focus on performance, flexibility, and production-readiness. If you're working with robotics, autonomous vehicles, drones, or intelligent devices, learning ROS2 is an essential skill.

In this blog, I'll introduce ROS2 and walk through some of the most common commands you'll use in daily development — covering workspace management, nodes, topics, rosbag recording, and RViz visualization.

What is ROS2?

ROS2 is a flexible framework for writing robot software. It provides tools, libraries, and conventions to simplify the task of creating complex and robust robot behavior across a wide variety of robotic platforms.

Compared to ROS1, ROS2 improves in areas like:

• Multi-platform support (Linux, Windows, macOS)
• Real-time capability
• Better security
• Middleware flexibility (DDS-based)
• Production-readiness for industrial use

Key Differences Between ROS1 and ROS2

While ROS1 laid the foundation for open-source robotics development, ROS2 was built to address its limitations and meet modern robotics needs. Here are the main differences:

In short, ROS2 is not just an "update" of ROS1 — it’s a fundamental re-architecture to make ROS ready for the future of robotics.

Essential ROS2 Commands

1. Workspace Setup

A workspace is where you organize your ROS2 packages. You’ll build and source your workspace to compile and run your robot applications.

 1# Source ROS2 environment
 2source /opt/ros/<ros2-distro>/setup.bash
 3
 4# Create a workspace
 5mkdir -p ~/ros2_ws/src
 6cd ~/ros2_ws
 7
 8# Build the workspace
 9colcon build
10
11# Source the workspace (after build)
12source install/setup.bash
13
14# Launch a launch file
15ros2 launch <package_name> <launch_file_name>

Notes:

• Replace <ros2-distro> with your installed version, e.g., humble, iron, foxy.
• Always source your workspace after building it so that ROS2 can find your new packages.

2. Working with Nodes and Topics

In ROS2, nodes are basic processes that perform computation. Topics are used for sending and receiving messages between nodes.

Node Commands

1# List all running nodes
2ros2 node list
3
4# Get detailed info about a specific node
5ros2 node info /<node_name>

Topic Commands

1# List all available topics
2ros2 topic list
3
4# Get information about a topic (like message type)
5ros2 topic info /<topic_name>
6
7# Print (echo) live messages from a topic
8ros2 topic echo /<topic_name>

Service Commands

ROS2 services are request-response communication types:

1# Call a service
2ros2 service call /<service_name> <service_type> "<request_data>"

Example:

1ros2 service call /reset_robot std_srvs/srv/Empty "{}"

3. Recording and Playing Data with Rosbag

Rosbag allows you to record and replay ROS2 messages. It's invaluable for testing and debugging without needing live hardware.

1# Record all topics
2ros2 bag record -a
3
4# Play back a recorded bag file
5ros2 bag play <bag_file_name>.db3

Tip: .db3 is the default format (SQLite3 database) for ROS2 bag files.

4. Visualizing Data with RViz2

RViz2 is a powerful visualization tool for ROS2, helping you view sensor data, robot models, and more in a graphical environment.

Install RViz2

1# Install rviz2 package
2sudo apt-get install ros-<ros2-distro>-rviz2

Example:

1sudo apt-get install ros-humble-rviz2

Launch RViz2

1rviz2

You can load robot models, display sensor topics like point clouds, lasers, maps, and more in real-time.