ROS2 Crash Course

Welcome to the workshop!

This workshop consists of 3 lectures that will take you through ROS2 and all its core concepts. They should equip you with the knowledge that will enable you to create your own ROS2-enabled projects as well as work with any ROS-enabled robots.

• Lecture 1: What is ROS?
  • Overview of ROS
  • The history of ROS
  • Why use ROS?
• Lecture 2: Working with ROS
  • The ROS Graph
  • ROS Actions
• Lecture 3: The ROS Ecosystem
  • Managing ROS workspaces
  • Simulation with ROS
  • Creating packages

Intended Learning Outcomes:

By the end of this 3-day workshop, you should be able to:

• Develop custom ROS2 packages that include custom nodes, topics and actions using Python
• Interact with and program ROS-enabled robots

Setup Requirements

Hardware

This course was primarily built around the Create3 educational robot as its primary demonstration platfom, so a working Create3 robot is required.

In cases where such a setup is not feasible, very similar activities can be created and demonstrated using the Gazebo simulation provided in the Create3 Simulation Packages, although this does require that students have powerful enough devices to comfortably run Gazebo.

Software

The software requirements for this course are relatively minimal:

1. A working Ubuntu Focal installation
   • You can follow this guide to install Ubuntu on your machine
   • You can also install Ubuntu on a virtual machine using this guide
2. A working ROS2 Galactic installation
   • You can install ROS2 Galactic following the official guide
   • ROS2 Galactic is specifically used as it was the version supported by the Create3 at the time of making this course. A new ROS2 Humble release was recently released, though it requires Ubuntu 22.
3. The Gazebo11 package
   • You can install it using this guide
4. The iRobot Create3 Messages package
   • You can build it from source or simply install the package using :

     sudo apt install -y ros-galactic-irobot-create-msgs

Frequently Asked Questions

Building and maintaining a reliable conection with ROS2 robots over wifi using a virtual machine setup can be challenging at times. This section will attempt to provide easy solutions to reccuring problems faced during the course:

Q: How do I change my ROS_DOMAIN_ID?

A: The first and easiest variable to rule out is the ROS_DOMAIN_ID variable. If your device and the robot you're connecting to use different domain IDs, you will not be able to interact with one another at all.

Your ROS_DOMAIN_ID environment variable is usually set in your .bashrc file, to edit it, you can use the following command

gedit ~/.bashrc

This should open your .bashrc file using a standard text editor. Scroll down to the bottom of your file and you should see a line similar to this (Add it if it is not there):

export ROS_DOMAIN_ID=1

Change your ID accordingly and save your file

Note: There should not be multiple lines like the one above, as only the line that is closest to the end of the file will be used. Make sure to scroll to the last line as gedit is sometimes bugged on some machines

To confirm your changes have taken effect, open a new terminal and entering the following command:

echo $ROS_DOMAIN_ID

This should now output the correct domain ID.

Q: How do I correctly configure my network settings on a virtual machine

A: Most of the time, you will not be able to successfully connect to other ROS2 devices over the network if your virtual machine does not use a bridged adapter network configuration. This guide is useful for VirtualBox users. A similar setting is also available in VMWare.