Book Image

Learning ROS for Robotics Programming

By : Aaron Martinez, Enrique Fernández
Book Image

Learning ROS for Robotics Programming

By: Aaron Martinez, Enrique Fernández

Overview of this book

<p>Both the amateur and the professional roboticist who has ever tried their hand at robotics programming will have faced with the cumbersome task of starting from scratch, usually reinventing the wheel. ROS comes with a great number of already working functionalities, and this book takes you from the first steps to the most elaborate designs possible within this software framework.</p> <p>"Learning ROS for Robotics Programming" is full of practical examples that will help you to understand the framework from the very beginning. Build your own robot applications in a simulated environment and share your knowledge with the large community supporting ROS.</p> <p>"Learning ROS for Robotics Programming" starts with the basic concepts and usage of ROS in a very straightforward and practical manner. It is a painless introduction to the fascinating world of robotics, covering sensor integration, modeling, simulation, computer vision, and navigation algorithms, among other topics.</p> <p>After the first two chapters, concepts like topics, messages, and nodes will become daily bread. Make your robot see with HD cameras, or navigate avoiding obstacles with range sensors. Furthermore, thanks to the contributions of the vast ROS community, your robot will be able to navigate autonomously, and even recognize and interact with you, in a matter of minutes.</p> <p>"Learning ROS for Robotics Programming" will give you all the background you need to know in order to start in the fascinating world of robotics and program your own robot. Simply, you put the limit!</p>
Table of Contents (16 chapters)
Learning ROS for Robotics Programming
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Inspecting what is going on


When our system is running, we might have several nodes and even more topics publishing messages and connected by subscription among nodes. Also, we might have some nodes providing services as well. For large systems, it is important to have some tools that let us see what is running at a given time. ROS provides us with some basic but powerful tools to do so, and also to detect a failure in any part of the nodes graph; that is, the architecture that emerges from the connection of ROS nodes using topics.

Listing nodes, topics, and services

In our honest opinion, we should start with the most basic level of introspection. We are going to see how to obtain the list of nodes running, and topics and services available at a given time. Although extremely simple, this is very useful and robust.

  • To obtain the list of nodes running use:

    rosnode list
    
  • The topics of all nodes are listed using:

    rostopic list
    
  • And, similarly, all services are shown by:

    rosservice list
    

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