Learning ROS for Robotics Programming gives you a comprehensive review of ROS tools. ROS is the Robot Operating System framework, which is used nowadays by hundreds of research groups and companies in the robotics industry. But it is also the painless entry point to robotics for nonprofessional people. You will see how to install ROS, start playing with its basic tools, and you will end up working with state-of-the-art computer vision and navigation tools.
The content of the book can be followed without any special devices, and each chapter comes with a series of source code examples and tutorials that you can run on your own computer. This is the only thing you need to follow in the book. However, we also show you how to work with hardware, so that you can connect your algorithms with the real world. Special care has been taken in choosing devices which are affordable for amateur users, but at the same time the most typical sensors or actuators in robotics research are covered.
Finally, the potential of ROS is illustrated with the ability to work with whole robots in a simulated environment. You will learn how to create your own robot and integrate it with the powerful navigation stack. Moreover, you will be able to run everything in simulation, using the Gazebo simulator. We will end the book by providing a list of real robots available for simulation in ROS. At the end of the book, you will see that you can work directly with them and understand what is going on under the hood.
Chapter 1, Getting Started with ROS, shows the easiest way you must follow in order to have a working installation of ROS. You will see how to install different distributions of ROS, and you will use ROS Fuerte in the rest of the book. How to make an installation from Debian packages or compiling the sources, as well as making installations in virtual machines, have been described in this chapter.
Chapter 2, The ROS Architecture with Examples, is concerned with the concepts and tools provided by the ROS framework. We will introduce you to nodes, topics, and services, and you will also learn how to use them. Through a series of examples, we will illustrate how to debug a node or visualize the messages published through a topic.
Chapter 3, Debugging and Visualization, goes a step further in order to show you powerful tools for debugging your nodes and visualize the information that goes through the node's graph along with the topics. ROS provides a logging API which allows you to diagnose node problems easily. In fact, we will see some powerful graphical tools such as rxconsole and rxgraph, as well as visualization interfaces such as rxplot and rviz. Finally, this chapter explains how to record and playback messages using rosbag and rxbag.
Chapter 4, Using Sensors and Actuators with ROS, literally connects ROS with the real world. This chapter goes through a number of common sensors and actuators that are supported in ROS, such as range lasers, servo motors, cameras, RGB-D sensors, and much more. Moreover, we explain how to use embedded systems with microcontrollers, similar to the widely known Arduino boards.
Chapter 5, 3D Modeling and Simulation, constitutes one of the first steps in order to implement our own robot in ROS. It shows you how to model a robot from scratch and run it in simulation using the Gazebo simulator. This will later allow you to use the whole navigation stack provided by ROS and other tools.
Chapter 6, Computer Vision, shows the support for cameras and computer vision tasks in ROS. This chapter starts with drivers available for FireWire and USB cameras, so that you can connect them to your computer and capture images. You will then be able to calibrate your camera using ROS calibration tools. Later, you will be able to use the image pipeline, which is explained in detail. Then, you will see how to use several APIs for vision and integrate OpenCV. Finally, the installation and usage of a visual odometry software is described.
Chapter 7, Navigation Stack – Robot Setups, is the first of two chapters concerned with the ROS navigation stack. This chapter describes how to configure your robot so that it can be used with the navigation stack. In the same way, the stack is explained, along with several examples.
Chapter 8, Navigation Stack – Beyond Setups, continues the discussion of the previous chapter by showing how we can effectively make our robot navigate autonomously. It will use the navigation stack intensively for that. This chapter shows the great potential of ROS using the Gazebo simulator and rviz to create a virtual environment in which we can build a map, localize our robot, and do path planning with obstacle avoidance.
Chapter 9, Combining Everything – Learn by Doing, builds from the previous chapters and shows a number of robots which are supported in ROS using the Gazebo simulator. In this chapter you will see how to run these robots in simulation and perform several of the tasks learned in the rest of the book, especially those related to the navigation stack.
This book was written with the intention that almost everybody can follow it and run the source code examples provided with it. Basically, you need a computer with a Linux distribution. Although any Linux distribution should be fine, it is recommended that you use a recent version of Ubuntu. Then you will use ROS Fuerte, which is installed according to the instructions given in Chapter 1, Getting Started with ROS. For this distribution of ROS, you will need a version of Ubuntu prior to 12.10 because since this version Fuerte is no longer supported.
Regarding the hardware requirements of your computer, in general any computer or laptop is enough. However, it is advisable to use a dedicated graphic card in order to run the Gazebo simulator. Also, it will be good to have a good number of peripherals, so that you can connect several sensors and actuators, including cameras and Arduino boards.
You will also need Git (the git-core Debian package) in order to clone the repository with the source code provided with this book. Similarly, you are expected to have a basic knowledge of the Bash command line, GNU/Linux tools, and some C/C++ programming skills.
This book is targeted at all robotics developers, from amateurs to professionals. It covers all the aspects involved in a whole robotic system and shows how ROS helps with the task of making a robot really autonomous. Anyone who is learning robotics and has heard about ROS but has never tried it will benefit from this book. Also, ROS beginners will learn advance concepts and tools of this framework. Indeed, even regular users may learn something new from some particular chapters. Certainly, only the first three chapters are intended for new users; so those who already use ROS may skip these ones and go directly to the rest.
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meanings.
Code words in text are shown as follows: "The *-ros-pkg contributed packages are licensed under a variety of open source licenses."
A block of code is set as follows:
<package>
<description brief="short description">
long description,
</description>
<author>Aaron Martinez, Enrique Fernandez</author>
<license>BSD</license>
<url>http://example.com/</url>
<depend package="roscpp"/>
<depend package="common"/>
<depend package="otherPackage"/>
<versioncontrol type="svn" url="https://urlofpackage/trunk"/>
<export>
<cpp cflags="-I${prefix}/include" lflags="-L${prefix}/lib -lros"/>
</package>When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
<launch>
<node pkg="chapter3_tutorials" type="example1"
name="example1" output="screen"
launch-prefix="xterm -e gdb --args"/>
</launch>Any command-line input or output is written as follows:
$ rosrun book_tutorials tutorialX _param:=9.0
New terms and important words are shown in bold. Words that you see on the screen, in menus, or dialog boxes for example, appear in the text like this: "We must have clicked on the Play button at least once."
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