ROS 2 Tutorial: turtlesim, Gazebo and the Pluto drone

Hands-on ROS 2 labs by Drona Aviation. You drive a simulated turtle, fly a simulated quadcopter in Gazebo, then fly a real Pluto drone, using the same few lines of Python each time.

Ubuntu 22.04 with ROS 2 Humble only. Other Ubuntu versions and ROS 2 distributions are not supported; the install script refuses to run on anything else.

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1. What's here

	What you do	Needs
Lab 1 — Turtlesim	Drive a 2D turtle from the keyboard, the terminal and Python: publishers and subscribers	ROS 2
Lab 2 — Gazebo drone	Fly a simulated X3 quadcopter through the ROS ↔ Gazebo bridge, by keyboard and by script; read its height	Gazebo Fortress
Lab 3 — Pluto drone	Fly a real Pluto over Wi-Fi and read its telemetry	A Pluto drone, 2 m of clear floor
Extra A	Topics, services, actions and parameters on the command line	ROS 2
Extra B	Your own ROS 2 package: workspace, colcon, launch files	colcon

How to use it:

1. Install and verify (sections 2–3 below).
2. Open VS Code with four terminals (section 4).
3. Follow LAB_HANDOUT.md for every lab, in order.
4. Finished a lab early? TASKS.md has eight coding tasks: squares, polygons, a staircase, holding a height.

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2. Install

First, get the tutorial files into your home folder:

sudo apt update && sudo apt install -y git
git clone https://github.com/DronaAviation/ROS2_Tutorial26.git ~/ROS2_Tutorial

Keep the folder name ~/ROS2_Tutorial: every command in this tutorial uses that path. To get updates later: cd ~/ROS2_Tutorial && git pull.

Everything else in this section is also in install.sh, which runs the same commands:

bash ~/ROS2_Tutorial/install.sh

Takes 15–40 minutes and is safe to re-run. Read on if you want to see each step, or if a step fails.

2.1 ROS 2 Humble

These are the official steps from docs.ros.org (Humble → Installation → Ubuntu deb packages).

Locale

sudo apt update && sudo apt install locales
sudo locale-gen en_US en_US.UTF-8
sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
export LANG=en_US.UTF-8

Enable Universe, install curl

sudo apt install software-properties-common
sudo add-apt-repository universe
sudo apt update && sudo apt install curl -y

Add the ROS 2 apt source

export ROS_APT_SOURCE_VERSION=$(curl -s https://api.github.com/repos/ros-infrastructure/ros-apt-source/releases/latest | grep -F "tag_name" | awk -F'"' '{print $4}')
curl -L -o /tmp/ros2-apt-source.deb "https://github.com/ros-infrastructure/ros-apt-source/releases/download/${ROS_APT_SOURCE_VERSION}/ros2-apt-source_${ROS_APT_SOURCE_VERSION}.$(. /etc/os-release && echo ${UBUNTU_CODENAME:-${VERSION_CODENAME}})_all.deb"
sudo dpkg -i /tmp/ros2-apt-source.deb

Upgrade, then install

sudo apt update
sudo apt upgrade
sudo apt install ros-humble-desktop ros-dev-tools

Do not skip apt upgrade on a fresh 22.04. The ROS 2 docs warn that installing ROS 2 before systemd/udev are updated can remove critical system packages.

ros-humble-desktop includes the ros2 tools, rclpy, turtlesim, rqt_graph and RViz. ros-dev-tools includes colcon and rosdep.

Check

source /opt/ros/humble/setup.bash
ros2 run turtlesim turtlesim_node

Expected: a window with a turtle. Ctrl+C to stop. (You do not need to add anything to ~/.bashrc — env.sh sources ROS 2 for you.)

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2.2 Gazebo and the bridge (Lab 2)

ROS 2 Humble pairs with Gazebo Fortress (the ign commands).

sudo apt install ros-humble-ros-gz ros-humble-teleop-twist-keyboard

This installs Gazebo Fortress, ros_gz_bridge, and the keyboard controller used in Experiment 2E. Then download the drone models once, so the first start of Lab 2 does not spend minutes downloading:

ign fuel download -u "https://fuel.gazebosim.org/1.0/OpenRobotics/models/X3 UAV"
ign fuel download -u "https://fuel.gazebosim.org/1.0/OpenRobotics/models/X4 UAV Config 1"

Check:

ign gazebo -r multicopter_velocity_control.sdf

Expected: Gazebo opens with two drones on the ground. Close it.

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2.3 Pluto drone packages (Lab 3) and build tools

System packages

sudo apt install python3-colcon-common-extensions python3-pip
pip3 install --user pynput

Package	Used by
python3-colcon-common-extensions	colcon build (Pluto workspace; Extra B in the handout)
python3-pip	installing pynput
pynput	the keyboard control node (drone_comb.launch.py)

Build the Pluto workspace

The Pluto ROS 2 packages come from Drona Aviation's pluto_ros2_package repository. They are built into their own workspace, ~/pluto_ws, which env.sh sources automatically.

source /opt/ros/humble/setup.bash
mkdir -p ~/pluto_ws/src
cd ~/pluto_ws/src
git clone https://github.com/DronaAviation/pluto_ros2_package.git
cd ~/pluto_ws
colcon build --symlink-install

Expected: Summary: 3 packages finished (custom_msgs, plutodrone, plutoserver). Warnings about setup.py / easy_install deprecation are normal.

If you keep the workspace somewhere else, set PLUTO_WS at the top of env.sh.

Check

source ~/pluto_ws/install/setup.bash
ros2 interface show custom_msgs/msg/PlutoMsg

Expected: the message fields (int64 rc_roll … bool is_auto_pilot_on).

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Install problems

What you see	Fix
E: Unable to locate package ros-humble-desktop	The "Add the ROS 2 apt source" step did not complete, or you are not on 22.04. Run apt policy ros-humble-desktop; if it shows no candidate, redo that step and sudo apt update.
dpkg: error … ros2-apt-source	ROS_APT_SOURCE_VERSION came back empty (no network to api.github.com). Re-run the export line and check it prints a version with echo $ROS_APT_SOURCE_VERSION.
colcon: command not found	sudo apt install python3-colcon-common-extensions, then open a new terminal.
colcon build fails in custom_msgs	sudo apt install ros-humble-rosidl-default-generators, then rm -rf ~/pluto_ws/build ~/pluto_ws/install and build again.
ModuleNotFoundError: No module named 'pynput'	pip3 install --user pynput, in the same Python ROS uses (which python3 → /usr/bin/python3).
ign: command not found after 2.2	Open a new terminal; if still missing, sudo apt install ignition-fortress.

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3. Verify

bash ~/ROS2_Tutorial/check_setup.sh

Expected: one PASS line per check, ending All checks passed. This laptop is ready. Each FAIL prints the command that fixes it underneath. Resolve every failure before Lab 1; the labs assume a passing check.

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4. VS Code, the four terminals and the setup line

1. Install VS Code (sudo snap install code --classic, or the .deb from code.visualstudio.com).

2. In a terminal:

   cd ~/ROS2_Tutorial
   code .

3. Open LAB_HANDOUT.md, press Ctrl+Shift+V to see it rendered, and drag that tab to the left half.

4. Open a terminal with **Ctrl+** (the backtick key). Click the **split** icon in the terminal panel three times, so you have **four** terminals. Right-click each → **Rename** → T1, T2, T3, T4`.

You should see:

+---------------------------+---------------------------+
|                           |  T1          |  T2        |
|   LAB_HANDOUT.md          |--------------+------------|
|                           |  T3          |  T4        |
+---------------------------+---------------------------+

Small screen? Ctrl+B hides the file list and gives the handout more room.

What each terminal is for, in every lab:

Terminal	Job	Lab 1	Lab 2	Lab 3
T1	The robot	turtlesim_node	Gazebo	plutonode
T2	A helper that keeps running	keyboard control	bridge	plutoserver
T3	Your commands and scripts	commands, turtle_circle.py	commands, keyboard, sim_drone.py	keyboard, commands, pluto_flight.py
T4	Watching messages	turtle_pose.py, topic echo	topic echo, sim_drone_pose.py	topic echo

The setup line

Run this in every terminal, first, every time you open a new one:

source ~/ROS2_Tutorial/env.sh

Expected: ROS 2 humble ready (this laptop only). Tutorial folder: /home/<you>/ROS2_Tutorial

It loads ROS 2, loads the Pluto packages, sets ROS_LOCALHOST_ONLY=1 (restricting ROS 2 discovery to this machine, so nodes on other laptops on the same network are neither seen nor controlled), and changes into the tutorial folder. Skip it and you get ros2: command not found, or two of your programs can't see each other.

Optional: to make it automatic in every new terminal, run once:

echo "source ~/ROS2_Tutorial/env.sh" >> ~/.bashrc

From then on, every new terminal starts in ~/ROS2_Tutorial and keeps ROS 2 on this laptop only, including later for other projects. To undo it:

sed -i '/ROS2_Tutorial\/env.sh/d' ~/.bashrc

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Terminal tips

• Copy / paste in a terminal: Ctrl+Shift+C / Ctrl+Shift+V. Plain Ctrl+C does not copy: it stops the program.
• A terminal that is running a program can't take a new command. Use another one.
• Ctrl+C stops the program in that terminal. Each lab ends with a Tidy up section that lists which terminals to stop, in which order, so the next lab starts from a clean state.
• Copying a command from the handout: select it with the mouse and press Ctrl+C (in the handout, Ctrl+C copies; only in a terminal does it stop the program), then Ctrl+Shift+V in the terminal. On GitHub, each code box also has a copy icon at its top-right.

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5. Folder layout

ROS2_Tutorial/
├── README.md              this page: install and setup
├── LAB_HANDOUT.md         every lab, step by step
├── TASKS.md               coding tasks for after Labs 1 and 2
├── install.sh             section 2 as one script
├── env.sh                 the setup line runs this
├── check_setup.sh         checks the laptop is ready
├── 1_turtlesim/
│   ├── turtle_circle.py   publisher: drives the turtle in one circle
│   └── turtle_pose.py     subscriber: prints where the turtle is
├── 2_gazebo/
│   ├── sim_drone.py       publisher: flies the simulated drone
│   └── sim_drone_pose.py  subscriber: prints where the simulated drone is
├── 3_pluto/
│   ├── pluto_flight.py    publisher: take off, hover, land, disarm
│   └── pluto_telemetry.py service server: receives the drone's sensor data
└── 4_workspace/
    └── tutorial_pkg/      a complete ROS 2 Python package (Extra B)

Update to the latest version at any time:

cd ~/ROS2_Tutorial && git pull

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6. Common problems

Most problems come down to one of four things. Check them in this order:

1. Is the other program running? → ros2 node list
2. Is the topic name exactly the same? → ros2 topic list (one typo = a new, empty topic)
3. Is the message type the same? → ros2 topic info <topic>
4. Did every terminal run the setup line? → printenv | grep ROS must show ROS_DISTRO=humble and ROS_LOCALHOST_ONLY=1

You see	Fix
ros2: command not found	Run the setup line in this terminal
ModuleNotFoundError: No module named 'rclpy'	Run the setup line. If a Python virtual environment is active, type deactivate
A script prints Waiting for a subscriber on …	Start the other side (turtlesim, the bridge, plutonode)
A robot on another laptop responds to your commands	A terminal skipped the setup line, so ROS_LOCALHOST_ONLY is unset and discovery crossed the network. Run the setup line in every terminal, then restart the programs
yaml / Failed to populate field after topic pub	Retype the quotes as plain ", keep a space after every colon
Ctrl+C doesn't copy	It stops the program. Use Ctrl+Shift+C

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More: ROS 2 Humble tutorials · Drona Aviation on GitHub