Morgan Quigley - Programming Robots with ROS: A Practical Introduction to the Robot Operating System

by Morgan Quigley , Brian Gerkey , and William D. Smart

Copyright 2016 Morgan Quigley, Brian Gerkey, and William D. Smart. All rights reserved.

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ROS, the Robot Operating System, is an open source framework forgetting robots to do things. ROS is meant to serve as acommon software platform for people who arebuilding and using robots. This common platform letspeople share code and ideas more readily and, perhaps moreimportantly, means that you do not have to spend years writingsoftware infrastructure before your robots start moving!

ROS has been remarkably successful. At the time of writing, in theofficial distribution of ROS, there are over 2,000 software packages,written and maintained by almost 600 people. Approximately 80commercially available robots are supported, and we can find at least1,850 academic papers that mention ROS. We no longer have to writeeverything from scratch, especially if were working with one of themany robots that support ROS, and can spend more time thinking aboutrobotics, rather than bit-fiddling and device drivers.

ROS consists of a number of parts:

1. A set of drivers that let you read data from sensors and sendcommands to motors and other actuators, in an abstracted,well-defined format. A wide variety of popular hardware issupported, including a growing number of commercially availablerobot systems.
2. A large and growing collection of fundamental robotics algorithmsthat allow you to build maps of the world, navigate around it,represent and interpret sensor data, plan motions, manipulateobjects, and do a lot of other stuff. ROS has become very popular inthe robotics research community, and a lot of cutting-edgealgorithms are now available in ROS.
3. All of the computational infrastructure that allows you to movedata around, to connect the various components of a complex robotsystem, and to incorporate your own algorithms. ROS is inherentlydistributed and allows you to split the workload across multiplecomputers seamlessly.
4. A large set of tools that make it easy to visualize the state of therobot and the algorithms, debug faulty behaviors, and record sensordata. Debugging robot software is notoriously difficult, and thisrich set of tools is one of the things that make ROS as powerful asit is.
5. Finally, the larger ROS ecosystem includes an extensive set ofresources, such as a wiki that documents many of the aspects of theframework, a question-and-answer site where you can ask for help andshare what youve learned, and a thriving community of users anddevelopers.

So, why should you learn ROS? The short answer is because it willsave you time. ROS provides all the parts of a robot software systemthat you would otherwise have to write. It allows you to focus on theparts of the system that you care about, without worrying about the partsthat you dont care about.

Why should you read this book? Theres a lot of material on the ROSwiki, including detailed tutorials for many aspects of the framework.A thriving user community is ready to answer your questions onhttp://answers.ros.org. Why not just learn ROS from these resources?What weve tried to do in this book is to lay things out in a moreordered way and to give comprehensive examples of how you can use ROSto do interesting things with real and simulated robots. Weve alsotried to include tips and hints about how to structure your code, howto debug your code when it causes the robot to do somethingunexpected, and how to become part of the ROS community .

Theres a fair amount of complexity in ROS, especially if youre not aseasoned programmer; distributed computation, multithreading,event-driven programming, and a host of other concepts lie at the heartof the system. If youre not already familiar with at least some ofthese, ROS can have a daunting learning curve. This book is anattempt to flatten out that curve a bit by introducing you to thebasics of ROS and giving you some practical examples of how to use itfor real applications on real (and simulated) robots.