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

Plotting scalar data


Scalar data can easily be plotted with some generic tools already available in ROS. Scalar data cannot be plotted, rather each scalar field has to be plotted separately. This is the reason we talk about scalar data because most nonscalar structures are better represented with ad hoc visualizers, some of which we will see later; for instance, images, poses, and orientation/attitude.

Creating a time series plot with rxplot

In ROS, scalar data can be plotted as a time series over the time provided by the timestamps of the messages. Then, we will plot our scalar data in the y axis. The tool to do so is rxplot. It has a powerful argument syntax that allows us to specify several fields of a structured message (in a concise manner as well).

To show rxplot in action, we are going to use the example4 node since it publishes a scalar and a vector (nonscalar) in two different topics, which are temp and accel respectively. The values put in these messages are synthetically generated...