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1. Introduction to ROS 2

1. Overview of ROS 2​

ROS 2 is the second-generation Robot Operating System, an upgrade to ROS 1 that addresses many of its limitations. The first ROS 2 release, Arden, was published in 2017. Through continuous updates and optimizations, ROS 2 now has stable long-term support releases.

As with ROS 1, the Linux distribution version must match the ROS 2 version. The corresponding versions are shown below.

ROS 2 Version Compatibility

note

Download the appropriate ROS 2 version for your Linux distribution. This course uses the Humble version as the reference. The programs and examples provided in this course are applicable across all ROS 2 versions.

2. Features of ROS 2​

2.1 Full Multi-Platform Support​

ROS 2 fully supports the following platforms:

  • Ubuntu\
  • macOS\
  • Windows 10

2.2 Distributed Architecture​

The ROS master node has been eliminated. ROS 2 enables distributed node discovery, publish/subscribe, and request/response communication without a centralized master.

2.3 Real-Time Support​

ROS 2 introduces built-in support for real-time systems, making it suitable for industrial and safety-critical robotics applications.

2.4 New Programming Language Standards​

  • C++11
  • Python 3.5+

2.5 New Build System​

ROS 2 uses the Ament build system (replacing Catkin from ROS 1).

2.6 ROS 1 and ROS 2 Interoperability​

ROS 1 can communicate with ROS 2 via rosbridge, allowing hybrid system deployments.

3. Differences Between ROS 2 and ROS 1​

3.1 Platform Support​

ROS 1 primarily supports Linux and is most commonly used on Ubuntu.
ROS 2 supports:

  • Ubuntu
  • Windows
  • Embedded development boards

This makes ROS 2 far more flexible for modern deployments.

3.2 Programming Language​

C++​

ROS 1 core is based on C++03, whereas ROS 2 is built extensively on C++11.

Python​

  • ROS 1 uses Python 2
  • ROS 2 requires Python 3.5+
  • ROS 2 Foxy uses Python 3.8

3.3 Middleware​

ROS 1 requires starting roscore before any node can communicate. This master node handles all inter-node messaging.

ROS 2 completely removes this dependency. Instead, it introduces an abstract middleware interface based on the DDS (Data Distribution Service) standard. This allows ROS 2 to support:

  • Multiple QoS (Quality of Service) policies
  • High-reliability communication
  • Operation over different network types

ROS 2 Middleware Architecture

3.4 Compilation Commands​

  • ROS 1: catkin_make\
  • ROS 2: colcon build

ROS 2 adopts colcon as its official build tool for faster and more scalable builds.