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Chapter 10: ROS 2 Fundamentals - Overview

About This Chapter​

This chapter introduces ROS 2 (Robot Operating System 2), the industry-standard middleware for building robotic systems. ROS 2 provides the communication layer, tools, and libraries that enable different components of a robot (sensors, perception, control, actuators) to work together seamlessly.

Learning Objectives​

By the end of this chapter, you will be able to:

  • Understand ROS 2 architecture and core concepts (DDS, computational graph)
  • Create and configure ROS 2 packages with proper structure
  • Work with nodes, topics, services, and actions
  • Write Python code to build ROS 2 applications
  • Use launch files and parameter management
  • Build interconnected robotic systems

Chapter Structure​

ROS 2 Architecture and Core Concepts​

  • ROS 2 ecosystem and why it exists
  • DDS middleware fundamentals
  • Quality of Service (QoS) policies
  • Computational graph (nodes, topics, services, actions)
  • Comparison with ROS 1

Nodes and Communication Patterns​

  • Creating your first ROS 2 node
  • Publisher/Subscriber pattern (topics)
  • Request/Response pattern (services)
  • Long-running tasks pattern (actions)
  • Custom message types

Building ROS 2 Packages​

  • Ament build system
  • Package structure and organization
  • Dependencies and setup
  • Writing executable nodes
  • Testing and debugging

Launch Files and Parameter Management​

  • Launch file syntax and structure
  • Running multiple coordinated nodes
  • Parameter servers and dynamic reconfiguration
  • Node composition and namespacing
  • Real-world launch file patterns

Prerequisites​

  • Familiarity with Python 3.10+
  • Ubuntu 22.04 LTS (recommended for ROS 2 Humble)
  • Basic command-line skills
  • Chapter 1: Introduction to Physical AI

Key Technologies​

TechnologyVersionRole
ROS 2Humble (2022.12)Core middleware
Python3.10+Development language
rclpyLatestPython client library
DDSMultiple vendorsCommunication
colconLatestBuild system

Estimated Time​

  • Reading: 6-8 hours
  • Hands-on Practice: 8-10 hours
  • Total: 14-18 hours

What You'll Build​

In this chapter, you'll create:

  1. A simple publisher/subscriber system
  2. A service client and server
  3. An action server for robot control
  4. A complete ROS 2 package
  5. A launch file coordinating multiple nodes

All examples will be tested on Unitree G1 specifications and simulatable in Gazebo.

Next: 2.1 ROS 2 Architecture and Core Concepts