Learning ROS for Robotics Programming Second Edition: Take control of the Linux based Robot Operating System, and discover the tools, libraries, and conventions you need to create your own robots without the hassle.

In this section, you will learn the steps for installing ROS Hydro in your computer. This process has been based on the official installation page, which can be found at http://wiki.ros.org/hydro/Installation/Ubuntu.

We assume that you know what an Ubuntu repository is, and how to manage it. If you have any doubts about it, refer to https://help.ubuntu.com/community/Repositories/Ubuntu.

Before we start the installation, we need to configure our repositories. To do that, the repositories need to allow restricted, universe, and multiverse. To check if your Ubuntu accepts these repositories, click on the Ubuntu Software Center in the menu on the left-hand side of your desktop, as shown in the following screenshot:

Click on Edit | Software Sources and you will see the next window. Make sure that all the listed options are checked as shown in the following screenshot:

Normally these options are marked, so you should not have any problem with this step.

In this step, you have to select your Ubuntu version. It is possible to install ROS Hydro in various versions of the operating system. You can use any of them, but we recommend version 12.04 to follow the chapters of this book. Keep in mind that Hydro works in the Precise Pangolin (12.04), Quantal Quetzal (12.10), and the Raring Ringtail(13.04) versions of Ubuntu.

Once you've added the correct repository, your operating system will know where to download programs to install them into your system.

This step is to confirm that the origin of the code is correct and that no-one has modified the code or programs without the knowledge of the owner. Normally, when you add a new repository you have to add the keys of that repository, so it is added to your system's trusted list.

$ wget http://packages.ros.org/ros.key -O - | sudo apt-key add -

Now we can be sure that the code came from an authorized site and has not been modified.

We are ready to start the installation now, but before we do that it's better to make an update to avoid problems with the libraries and software with a version other than what ROS needs. This is done with the following command:

$ sudo apt-get update

ROS is huge; sometimes you will install libraries and programs that you will never use. Normally it has four different installations, but this depends on the final use. For example, if you are an advanced user, maybe you only need the basic installation for a robot without much space on the hard disc. For this book, we recommend you use the full installation because it will install everything necessary to practice the examples and tutorials.

It doesn't matter if you don't know what are you installing right now — rviz, simulators, navigation, and so on. You will learn everything in the upcoming chapters:

Before you can use ROS, you will need to initialize rosdep. The rosdep command line too enables you to easily install system dependencies for the source you want to compile and is required to run some core components in ROS. In ROS Fuerte you had to install rosdep after installing ROS, and it was known as a standalone tool. Now rosdep is installed in ROS by default. To initialize rosdep, you have to use the following commands:

$ sudo rosdep init 
$ rosdep update

Congratulations! If you are at this step, you have an installed version of ROS on your system! To start using it, the system needs to know the location of the executable or binary files as well as the other commands. To do so, normally you need to execute the next script; if you also install another ROS distro, you can work with both just by calling the script of the one you need each time, since this script simply sets your environment. Here we use the one for ROS Hydro, but just replace Hydro with Fuerte or Groovy if you want to try other distros:

$ source /opt/ros/hydro/setup.bash

If you type roscore in the shell, you will see something starting up. This is the best test for finding out if you have ROS, and if it is installed correctly.

Notice that if you open another shell and type roscore or other ROS commands, it does not work. This is because it is necessary to execute the script again to configure the global variables, the path where ROS is installed, and so on.

It is very easy to solve this; you just need to add the script at the end of your .bashrc script file so that when you start a new shell, the script will execute and you will have the environment configured.

The .bashrc file is within the user home (/home/USERNAME/.bashrc). It has the configuration of the shell or terminal, and each time the user opens the terminal, this file is loaded. So you can add commands or configuration to make the user's life easy. For this reason, we will add the script at the end of the .bashrc file, to avoid keying it in each time we open a terminal. We do this with the following command:

$ echo "source /opt/ros/hydro/setup.bash" >> ~/.bashrc 

To see the results, you have to execute the file using the next command, or close the current terminal and open another.

$ source ~/.bashrc

Some users need more than a single ROS distribution installed in their system. Your ~/.bashrc must only source the setup.bash of the version you are currently using, since the last call will override the environment set of the others. So you have several distros living in the same system and need to switch between them.

For example, you might have the following lines in your .bashrc file:

…
source /opt/ros/hydro/setup.bash
source /opt/ros/fuerte/setup.bash
source /opt/ros/electric/setup.bash
…

The ROS Electric version will be executed in this case. So you have to make sure that the version you are running is the last one in the file.

If you want to check the version used in a terminal, you can do so easily using the echo $ROS_DISTRO command.

Now, the next step is to install a command tool that will help us install other packages with a single command. This tool is based in Python, but don't worry, you don't need to know Python to use it. You will learn how to use this tool in the upcoming chapters:

To install this tool on Ubuntu, run the following command:

$ sudo apt-get install python-rosinstall

And that is all! You have a complete ROS system installed in your system. When I finish a new installation of ROS, I personally like to test two things: that roscore works, and turtlesim.

If you want to do the same,, type the following commands in different shells:

$ roscore
$ rosrun turtlesim turtlesim_node

And if everything is okay, you will see the following screenshot:

The first step is to download the VirtualBox installation file. The latest version at the time of writing this book is 4.3.12; you can download it from http://download.virtualbox.org/virtualbox/4.3.12/. If you're using Windows, you can download it from http://download.virtualbox.org/virtualbox/4.3.12/VirtualBox-4.3.12-93733-Win.exe.

Once installed, you need to download the image of Ubuntu; for this tutorial we will use a copy of Ubuntu with ROS Hydro installed. You can download it from http://nootrix.com/2014/04/virtualized-ros-hydro/.

For this version, the Nootrix team are using torrent to download the virtual machine; I tried this way to download the file and it works perfectly.

You can find different virtual machines with Ubuntu and ROS preinstalled, but we are going to use this version because it is referred to in the official pages of ROS.

Creating a new virtual machine with the downloaded file is very easy; just proceed with the following steps. Open VirtualBox and click on File | Import Appliance. Then click on Open appliance and select the ROSHydro.ova file downloaded earlier:

In the windows that follow, you can configure the parameters of the new virtual machine. Keep the default configuration and change only the name for the virtual system. This name is how you distinguish this virtual machine from others. Our recommendation is to put a descriptive name, in our case the name of this book:

Click on the Import button, and accept the software license agreement in the next window. You will see a progress bar. It means that VirtualBox is copying the file with the virtual image, and it is creating a new copy with the new name.

Notice that this process doesn't modify the original file ROS.ova, and you could create more virtual machines with different copies from the original file.

The process will take a few minutes depending on your computer. When it finishes, you can start your virtual machine by clicking on the Start button. Remember to select the right machine before you start it. In our case, we only have one but you could have more:

Sometimes, you will get an error as shown in the following screenshot. It is because your computer doesn't have the correct drivers to use the USB 2.0 controller. You can fix this by installing the Oracle VM VirtualBox Extension Pack, but you can also choose to disable the USB support to start using the virtual machine:

To disable the USB support, right-click over the virtual machine and select Settings. In the General tab, click on Ports | USB and uncheck the Enable USB 2.0 (EHCI) Controller, as shown in the following screenshot. Now you can restart the virtual machine and it should start without any problems.

Once the virtual machine starts, you should see the next window as seen in the following screenshot. It is the Ubuntu 12.04 OS with ROS installed:

When you finish these steps, you will have a full copy of ROS Hydro that can be used along with this book. You can run all the examples and stacks that we are going to work with. Unfortunately, VirtualBox has problems when working with real hardware, and it's possible that you may not be able to use this copy of ROS Hydro with the examples given in Chapter 4, Using Sensors and Actuators with ROS.

Before installing ROS on Beaglebone Black, we have to achieve some prerequisites. As this book is focused on ROS, we will list them without entering into detail. There is a lot of information about Beaglebone Black and Ubuntu ARM available on websites, forums, and books that you can check out.

First, we have to install an Ubuntu ARM distribution compatible with ROS. So, an image of Ubuntu ARM is needed. You can obtain an Ubuntu 13.04 Raring armhf using wget with the following command:

$ wget https://rcn-ee.net/deb/flasher/raring/BBB-eMMC-flasher-ubuntu-13.04-2013-10-08.img

Download the Ubuntu 13.04 armhf image and install it on your SD card. You can get more details on how to install Ubuntu on Bealgebone Black on eLinux at http://elinux.org/Beagleboard:Ubuntu_On_BeagleBone_Black#Ubuntu_Raring_On_Micro_SD.

The process described in the preceding webpage works fine, but we have to be careful with the version of Ubuntu used. As the website is periodically updated, they are now using Ubuntu 14.04, which is not compatible with ROS. We will use an Ubuntu 13.04 Raring armhf as mentioned earlier.

Once we have Ubuntu ARM on our platform, the Beaglebone Black network interfaces must be configured to provide access to the network. So, you will have to configure the network settings such as IP, DNS, and gateway.

Remember that the easiest way could be mounting the SD card in another computer and editing /etc/network/interfaces.

After setting up the network, we should install the packages, programs, and libraries that ROS will need such as CMake, Python, or Vim using the following commands:

$ sudo apt-get install cmake python-catkin-pkg python-empy python-nose python-setuptools libgtest-dev build-essential

$ sudo apt-get install g++ curl pkg-config libv4l-dev libjpeg-dev build-essential libssl-dev vim

The operating system for Beaglebone Black is set up for micro SD cards with 1-4 GHz. This memory space is very limited if we want to use a great part of the ROS Hydro packages. So in order to solve this situation, we can use SD cards with larger space and expand the file system to occupy all the space available with re-partitioning.

So if we want to work with a bigger memory space, it is recommended to expand the Beaglebone Black memory file system. This process is further explained at http://elinux.org/Beagleboard:Expanding_File_System_Partition_On_A_microSD.

You can do this by following the commands listed next:

Now we should be ready to install ROS. At this point, the process of installation is pretty similar to the PC installation previously explained in this chapter. So, we should be familiar with it. We will see that the main difference when installing ROS on BeagleBone Black is that we can't install the ROS full-desktop; we must install it package by package.

Now you will start setting up your local machine:

$ sudo update-locale LANG=C LANGUAGE=C LC_ALL=C LC_MESSAGES=POSIX

After this, we will configure the source lists depending on the Ubuntu version that we have installed in BeagleBone Black. The number of Ubuntu versions compatible with BeagleBone Black are limited, and only active builds can be found for Ubuntu 13.04 raring armhf, the most popular version of Ubuntu ARM.

As explained previously, this step is needed to confirm that the origin of the code is correct and that no-one has modified the code or programs without the knowledge of the owner:

$ wget http://packages.namniart.com/repos/namniart.key -O - | sudo apt-key add –

Before the installation of ROS packages, we must update the system to avoid problems of library dependencies.

$ sudo apt-get update

This part of the installation is slightly different for the Beaglebone Black. There are a lot of libraries and packages in ROS and not all of them compile fully on an ARM. So, it is not possible to make a full-desktop installation. It is recommended to install package by package to ensure that they will work on an ARM platform.

You can try to install ROS-base, known as ROS Bare Bones. ROS-base installs the ROS package along with the build and communications libraries but does not include the GUI tools:

$ sudo apt-get install ros-hydro-ros-base

We can install specific ROS packages by using the following command:

$ sudo apt-get install ros-hydro-PACKAGE

If we need to find the ROS packages available for BeagleBone Black, you can run the following command:

$ apt-cache search ros-hydro

For example, the following packages are the basics that work with ROS and can be installed individually using apt-get install:

$ sudo apt-get install ros-hydro-ros
$ sudo apt-get install ros-hydro-roslaunch
$ sudo apt-get install ros-hydro-rosparam
$ sudo apt-get install ros-hydro-rosservice

Although theoretically, not all the packages of ROS are supported by BeagleBone Black, in practice, we have been able to migrate entire projects developed on PC to BeagleBone Black. We tried a lot of packages, and we could only not install rviz.

The rosdep command-line tool must be installed and initialized before you can use ROS. This allows you to easily install libraries and solving system dependencies for the source you want to compile, and is required to run some core components in ROS. You can use the following commands to install and initialize rosdep:

$ sudo apt-get install python-rosdep
$ sudo rosdep init
$ rosdep update

If you have arrived at this step, congratulations because you have installed ROS in your BeagleBone Black. The ROS environment variables can be added to your bash, so they will be added every time a shell is launched:

$ echo "source /opt/ros/hydro/setup.bash" >> ~/.bashrc
$ source ~/.bashrc

We have to be careful if we have more than one version of ROS in our system. The bashrc setup must use the variables of the version being used only.

If we want to set up the environment in the current shell, we will run the following command:

$ source /opt/ros/hydro/setup.bash

Rosinstall is a common command-line tool in ROS that helps us to install packages easily. It can be installed on Ubuntu with the following command line:

$ sudo apt-get install python-rosinstall