INTRODUCTION TO ROBOT OPERATING SYSTEM (ROS)

If you are reading this, it is because you either are or you want to become a ROS developer. Basically a ROS developer is somebody who wants to build programs for robots based on ROS. Yeah, but what is ROS? How can I learn ROS? How can I start developing with it? What is the most optimal development environment for it? All those questions will be answered in the following pages. But before we start with the practical things, let’s answer some basic questions about what ROS is and why it can be the door through which you can become a developer for robots.

WHY ARE THERE NOT ENOUGH DEVELOPERS FOR ROBOTICS?

In general, software developers do not like to deal with hardware. It is very likely that you are a developer and never thought about entering the robotics realm. You probably think that by programming for robots, you would need to know about electronics and maybe even mechanics. You probably think that hardware and software are too coupled in robots, and that you cannot touch one thing without touching the other. For example, some years ago, I had to make the navigation system for a robot. However, our navigation program was not working at all. We thought that it was something wrong with the program, but after extensive review, we found that it actually was a problem with the electronics of the laser scanner that we used to localize the robot. There were some micro-interruptions in the voltage level that made the laser reboot. In order to find that error, we had to go to the basics and find where the problem within the physical laser was. For that, you need to mess with the electronics. You have to take the laser out of the robot, put it on your table, and start experimenting. Different voltages, different interruptions to the power, all in order to try to reproduce the effect in a controlled environment. That is a lot of interaction with the hardware.Interaction with hardware is something that many software developers don’t like. After all, they decided to become developers of software, not hardware!!

ROBOTICISTS PROGRAMMING ROBOTS

Due to that, the programming of robots has been done by roboticists, who are the people that build the robots. Maybe some of them are not directly involved in the creation of the robot, but definitely they have no problem getting into the hardware and trying to fix some hardware problems, in order to make their program work. But let’s face it, most roboticists are better developers than programmers. That is why robotics could benefit so much from having lots of expert programmers coming to the field. The good news is that getting developers into the field is more possible than ever. Thanks to the Robot Operating System, ROS, you can completely abstract the hardware from the software, so you can program a robot just by knowing the robot ROS API. By using the ROS API, you can forget about the hardware and just concentrate on the software that makes the robot do what you want.

WHAT IS THE ROBOT ROS API?

The ROS API is the list of ROS topics, services, action servers, and messages that a given robot is providing to give access to its hardware, that is, sensors and actuators. If you are not familiar with ROS, you may not understand what those terms mean. But simply put in the developers’ language, topics/services/messages are like the software functions you can call on a robot to get data from the sensors or make the robot take action. It also includes the parameters you can pass on to those functions. Most modern robot builders are providing off-the-shelf ROS APIs, like for example, ROS- Components shop that provides all its hardware running with a ROS API. If the robot you want to work with does not run ROS, you can still make the robot work with ROS by ROSifying it. To ROSify means to adapt your robot to work with ROS. To ROSify a robot usually requires knowledge to access the hardware. You need to learn how to communicate with the electronics that provide the sensor data or access the motors of the robot. In this series of ROS tutorials, we are not dealing with that subject because it gets out of scope for developers. But if you are interested in this topic, you can learn more about it in this Robot Creation Course.So for the rest of the tutorials, we will assume that you have access (or are willing to have access) to a robot that is ROSified.

WHAT IS ROS ANYWAY?

ROS stands for Robot Operating System. Even if it says so, ROS is not a real operating system since it goes on top of Linux Ubuntu. ROS is a framework on top of the O.S. that allows it to abstract the hardware from the software. This means you can think in terms of software for all the hardware of the robot. And that’s good news for you because this implies that you can actually create programs for robots without having to deal with the hardware. Yeah!

ROS FOR SERVICE ROBOTS

ROS is becoming the standard in robotics programming, at least in the service robots sector. Initially, ROS started at universities, but quickly spread into the business world. Every day, more and more companies and startups are basing their businesses in ROS. Before ROS, every robot had to be programmed using the manufacturer’s own API. This means that if you changed robots, you had to start the entire software again, apart from having to learn the new API. Furthermore, you had to know a lot about how to interact with the electronics of the robot in order to understand how your program was doing. The situation was similar to that of computers in the 80s, when every computer had its own operating system and you had to create the same program for every type of computer. ROS is for robots like Windows is for PCs, or Android for phones. By having a ROSified robot, that is, a robot that runs on ROS, you can create programs that can be shared among different robots. You can build a navigation program, that is a program to make a robot move around without colliding, for a four-wheeled robot built by company A and then use the same exact code to move a two-wheeled robot built by company B… or even use it on a drone from company C.

SOME COMMONLY ASKED QUESTIONS

Which operating system should be used with ROS?

ROS works on Linux Ubuntu or Linux Debian. Experimental support already exists for OSX and Gentoo, and a version for Windows in underway, but we really don’t recommend for you to use them yet, unless you are an expert. Check this page for more information about how to use ROS on those systems. If you don’t know how to work with Linux, I recommend you start with this free Linux for Robotics course.

HOW TO DEVELOP FOR ROBOTS WITH ROS

Now, if you are convinced you want to become a robotics developer, in this series of ROS tutorials, you are going to find the steps that you can take to become a ROS developer. We have divided the tutorial series into the following sections that should cover the whole development process: • Setting Up• Learning• Coding• Testing Let’s go, one by one. [irp posts=”14751″ name=”ROS for Beginners: How to Learn ROS”] To access the full guide, click the orange button below, or go to RobotIgniteAcademy.com.