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ROS 2 from Scratch

You're reading from   ROS 2 from Scratch Get started with ROS 2 and create robotics applications with Python and C++

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Product type Paperback
Published in Nov 2024
Publisher Packt
ISBN-13 9781835881408
Length 380 pages
Edition 1st Edition
Concepts
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Author (1):
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Edouard Renard Edouard Renard
Author Profile Icon Edouard Renard
Edouard Renard
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Table of Contents (20) Chapters Close

Preface 1. Part 1:Getting Started with ROS 2
2. Chapter 1: Introduction to ROS 2 – What Is ROS 2? FREE CHAPTER 3. Chapter 2: Installing and Setting Up ROS 2 4. Chapter 3: Uncovering ROS 2 Core Concepts 5. Part 2: Developing with ROS 2 – Python and C++
6. Chapter 4: Writing and Building a ROS 2 Node 7. Chapter 5: Topics – Sending and Receiving Messages between Nodes 8. Chapter 6: Services – Client/Server Interaction between Nodes 9. Chapter 7: Actions – When Services Are Not Enough 10. Chapter 8: Parameters – Making Nodes More Dynamic 11. Chapter 9: Launch Files – Starting All Your Nodes at Once 12. Part 3: Creating and Simulating a Custom Robot with ROS 2
13. Chapter 10: Discovering TFs with RViz 14. Chapter 11: Creating a URDF for a Robot 15. Chapter 12: Publishing TFs and Packaging the URDF 16. Chapter 13: Simulating a Robot in Gazebo 17. Chapter 14: Going Further – What To Do Next 18. Index 19. Other Books You May Enjoy

Creating a custom service interface

In Chapter 5, when we created the ROS 2 application with the number_publisher and number_counter nodes, we used an existing interface for the number topic. Since we wanted to publish an integer number, the example_interfaces/msg/Int64 interface seemed to be exactly what we needed. At this point, you know that you must avoid using the example_interfaces package for real applications, but for a first test, that wasn’t a problem.

We’re going to continue working on this application and add more functionalities so that we can practice with services. Here, we will focus on the number_counter node. For now now, in this node, every time we receive a message from the number topic, we’ll add this number to a counter and print the counter.

What we want to do is allow the number_counter node to reset the counter to a given number when we ask it to. For that, we will add a service server inside the node. Then, any other node can send...

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