Update docs/installation.md

docs/installation.md

+# Embedded computer
+## Description
+The system is an Ubuntu 18.04 with:
+* A user `irilab` with root permissions.
+* Another user `helena` with password `helena` and without root permissions.
+* Some extra packages:
+  * vim: A program to edit files from a terminal.
+  * byobu: To open multiples terminals on the remote machine, in this case the car, with just an ssh connection. In case of a lost connection, runninng another time byobu will open the terminals already opened.
+  * ssh: To be able to remotely connect to the robot.
+  * apt-utils:
+  * vim:
+  * wget:
+  * ca-certificates:
+  * xsdcxx:
+  * ntp: For time synchronization purposes.
+* Labrobotica repository added.
+* All the necessary drivers.
+* ROS Melodic: There are two wokspaces created: 
+  * **ana_ws** where there are all the basic nodes to start up the robot. This wokspace is intended to be updated and upgraded by labrobotica technical support team. This workspace is not intended to be modified by the user.
+  * **user_ws** intended to be used by the user to create his own packages. If there is a package with the same name on both workspaces the one on this workspace will be used; So any desired modification on a basic driver node should be done here on a copy of the original package.
+* Some useful personalizations:
+  * Unlimited terminal scrolling
+  * Av. pag and Re. pag to search command history.
+  * Changed color name on terminal to red.
+  * Increased bash_history size. 
+* A default NTP configuration te act as a time server.
 
+## Instructions
+If it is necessary to reinstall helena follow the instructions bellow:
+
+**1. Install Ubuntu:**
+
+Download [Ubuntu 18.04 image](https://releases.ubuntu.com/18.04/) and [create a bootable USB](https://ubuntu.com/tutorials/create-a-usb-stick-on-ubuntu#1-overview) with the image. Use the USB to install Ubuntu 18.04 on the robot. Use as **user name irilab** and as **computer name helena-embedded**.
+
+**2. Update and personalize Ubuntu:**
+
+* Install some extra packages:
+```bash
+sudo apt update && sudo apt upgrade -y && sudo apt dist-upgrade
+sudo apt install -y apt-utils vim wget ca-certificates xsdcxx ssh byobu ntp
+```
+
+* Av. pag and Re. pag to search command history: Edit */etc/inputrc*:
+```bash
+sudo vim /etc/inputrc
+```
+Uncomment the following lines:
+```
+"\e[5~": history-search-backward
+"\e[6~": history-search-forward
+```
+* Change color name on terminal and bash history size: Edit *~/.bashrc*:
+```bash
+vim ~/.bashrc
+```
+Increasse *HISTSIZE* and *HISTFILESIZE*.
+
+Uncomment the following line:
+```
+force_color_prompt=yes
+```
+Modify the following line changing [\033[01;**32**m\] to [\033[01;**31**m\]:
+```
+PS1='${debian_chroot:+($debian_chroot)}\[\033[01;31m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
+```
+
+Add labrobotica repository as explained on [labrobotica_how_to](https://gitlab.iri.upc.edu/labrobotica/labrobotica_how_to#from-debs)
+
+**3. Install ROS Melodic:**
+
+Follow the instructions on this [ROS tutorial](http://wiki.ros.org/melodic/Installation/Ubuntu) to install **ros-melodic-desktop-full**. Make sure to follow step 1.5 and 1.6.
+
+**4 Create the base ROS workspace, download robot packages and install dependencies:**
+
+```bash
+cd
+mkdir -p helena_ws/src
+mkdir -p helena_ws/rosinstall
+cd helena_ws/rosinstall
+wget -q https://gitlab.iri.upc.edu/labrobotica/ros/iri_ros_how_to/-/raw/master/rosinstall/iri_core.rosinstall
+wget -q https://gitlab.iri.upc.edu/labrobotica/ros/robots/helena/iri_helena_how_to/-/raw/master/rosinstalls/helena_common.rosinstall
+wget -q https://gitlab.iri.upc.edu/labrobotica/ros/robots/helena/iri_helena_how_to/-/raw/master/rosinstalls/helena_real.rosinstall
+cd ../src
+wstool init
+wstool merge -y -r ../rosinstall/iri_core.rosinstall
+wstool merge -y -r ../rosinstall/helena_common.rosinstall
+wstool merge -y -r ../rosinstall/helena_real.rosinstall
+wstool update -j 10
+rosdep install -q -y -i -r --from-paths .
+source /opt/ros/melodic/setup.bash
+cd ..
+catkin_make
+echo "source ~/helena_ws/devel/setup.bash" >> $HOME/.bashrc
+source ~/.bashrc
+```
+
+**5. Setup NTP server**
+
+Edit */etc/ntp.conf* and paste at the end of the file the following lines:
+```
+# Allow LAN machines to synchronize with this ntp server
+restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
+
+server 127.127.1.0
+fudge 127.127.1.0 stratum 10
+```
+
+# Development Computer