TurtleBot Lab Guide

• The booking system is available at https://cw.felk.cvut.cz/brute/student/reservation.php.
• Create a team of at most three students for the semestral work assignment in BRUTE.
• Each team can book one robot for four 45min time slots.
• Each team can book the playground only for a single 45min time slot.
• Every two slots contain a 15min break, so that the slots are aligned with the school schedule hours.
• Note: All the robots are already reserved for ARO students during the ARO lab slots. There is no need to book the robots for your ARO lab slot, just take one.

• Turn the robot on using the black power flip switch located on the side of each robot base.
• Turn on the robot NUC computer by pressing its power button.
• The robot is ready when its screen shows the Ubuntu desktop and the robot number.

Use the following command to login to your booked robot (turtle04 in this case) from one of the lab computers (machine name 'pc', username 'user'). The password is r0sr0s. The commands here are shown as displayed in a terminal, so do not type the prompt (e.g. user@pc:~$) again, only the command itself (e.g. ssh ros@turtle04).

user@pc:~$ ssh ros@turtle04
password:
A TurtleBot welcome message etc...
ros@turtle04:~$

Although one can also use all the robots numbered from one to seven, the robots turtle04, turtle06, turtle07 are equipped with all the hardware needed in the ARO course (RPLidar, RealSense).

If you want to login to the robots from your own laptop, you need to connect to the lab wi-fi hotspot:

SSID: e210bot
password: j6UsAC8a

The robots can be accessed via the domain names turtle04.local, turtle06.local, turtle07.local etc. on the wireless network.

In the rare case the local domain name system does not work, you may access the robots via their IP addresses instead of the domain names:

192.168.210.21  turtle01
192.168.210.22  turtle02
192.168.210.23  turtle03
192.168.210.24  turtle04
192.168.210.25  turtle05
192.168.210.26  turtle06
192.168.210.27  turtle07

On your computer, you can add these items to /etc/hosts to ensure the name resolution works.

Upload your ROS packages into ~/workspace/aro_student/. Create the workspace folder on the robot if it does not already exist:

ros@turtle04:~$ mkdir -p ~/workspace/aro_student/src

If the workspace exists, delete it and create it again:

ros@turtle04:~$ rm -r ~/workspace/aro_student
ros@turtle04:~$ mkdir -p ~/workspace/aro_student/src

The first suitable ROS package to copy to the robot is robot_coordination. It provides waypoint navigation services and a sample Python script to follow a predefined trajectory with the robot. One needs to extract the robot_coordination folder from the tar.gz archive before copying it to the TurtleBot computer.

To synchronize a folder robot_coordination (change this folder name later to your own folder containing a ROS package) to the workspace of turtle04, type the following command on your PC:

user@pc:~$ rsync -av --delete robot_coordination ros@turtle04:~/workspace/aro_student/src

The command transfers the data of the local folder robot_coordination via SSH over the network to the computer of TurtleBot turtle04.

Before shutting down the robot and leaving, do not forget to delete all your files on the TurtleBot:

ros@turtle04:~$ rm -r ~/workspace/aro_student

Another option is to run on the robot only the drivers and have the rest running on your computer. There is no need to transfer your workspace to the robot in this setup. For that to work, one has to ensure that nodes can establish connection in both ways—both from your computer to the robot and from the robot to your computer. Let the roscore and drivers run on the robot (turtle_start and rplidar.launch below). On your computer, you can run e.g.

source ~/path/to/your_workspace/devel/setup.bash
export ROS_MASTER_URI=http://turtle07:11311/
export ROS_IP=`ip -4 addr | grep -oP '(?<=inet\s)192\.168\.210\.\d+'`
roslaunch aro_slam live.launch

ROS_MASTER_URI tells the nodes what roscore to contact (pick your turtle), ROS_IP tells them to advertise topics using the IP address (which the robot can see) instead of the hostname (which it may not see).

On your computer, add static IP addresses of the robots to /etc/hosts to ensure the name resolution works. See Turtlebots' IP addresses above.

Activate ROS and basic TurtleBot packages:

ros@turtle04:~$ turtle_stop
ros@turtle04:~$ turtle_start

Activate the RPLidar if it is not already running:

ros@turtle04:~$ tmux new-window -t ros:3
ros@turtle04:~$ tmux send -t ros:3 "roslaunch rplidar_ros rplidar.launch" ENTER

Change the current directory to the catkin workspace, build it and source it:

ros@turtle04:~$ cd ~/workspace/aro_student
ros@turtle04:~/workspace/aro_student$ catkin build
ros@turtle04:~/workspace/aro_student$ source devel/setup.bash

Run any ROS nodes you wish, e.g. waypoint navigation from the robot_coordination package:

ros@turtle04:~$ rosrun robot_coordination robot_node 

When the waypoint navigation services are running, you can make the robot move by running the provided example script in another bash terminal, again while being logged in to the robot:

ros@turtle04:~$ rosrun robot_coordination path_following_simple.py 

See the README.md file in the robot_coordination package for more details.

To start the ICP SLAM node:

ros@turtle04:~$ roslaunch aro_slam live.launch

If you want to run a program requiring PyTorch, source the PyTorch virtual environment first:

ros@turtle04:~$ source ~/torchenv/bin/activate

• Run turtle_stop.
• Delete all your files on the TurtleBot, rm -r ~/workspace/aro_student.
• Turn off the NUC computer by pressing its power button.
• Turn off the robot by the black power flip switch.
• Park the robot in a charging station.