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Installation

This section provides a guide to install and configure the environment required to run the DJI Tello altitude control system on Raspberry Pi 4. It covers dependency installation, ROS 2 Humble setup, and development environment configurations.

System Requirements

Hardware Requirements

  • Raspberry Pi 4 or 5
  • Storage: 32 GB microSD card (Class 10)
  • DJI Tello Drone

Software Requirements

  • Operating System: Ubuntu 22.04 LTS (64-bit, ARM) or Ubuntu 24.04 LTS (64-bit, ARM)
  • ROS 2: Humble or Jazzy

Environment Setup

Update the system

sudo apt update && sudo apt upgrade -y
sudo apt install -y curl wget git python3-pip

ROS 2 Installation

For Ubuntu 22.04 Install ROS 2 Humble: ROS 2 Humble installation!

For Ubuntu 24.04 Install ROS 2 Jazzy: ROS 2 Jazzy installation!

Python Virtualenv Installation

To verify if virtualenv is ready installed, run: 

virtualenv --version

If virtualenv is not installed, run: 

sudo apt update && sudo apt install -y python3-virtualenv

Project Cloning and Creating the virtual environment

clone the repository and open the file: 

git clone https://github.com/LichtenbergCode/tello-pid-altitude-control-ros2.git
cd tello-pid-altitude-control-ros2

To create the virtual environment, run: 

virtualenv -p python3 ./venv

To use a virtual environment with ROS 2 you must tell colcon to ignore the directory that contains the files that manage the virtual environment: 

touch ./venv/COLCON_IGNORE

To ensure your ROS 2 distribution can access Python packages installed in your virtual environment, you need to explicitly add the virtual environment's Python path to ROS's Python system path. This bridges the gap between your isolated Python environment and the ROS 2 ecosystem.

Add the following lines to your virtual environment's activation script to automatically configure the Python path when the environment is activated: 

export PYTHONPATH=${PYTHONPATH}:/path-to-your-env/lib/python3.10/site-packages

Example: Modify Virtual Environment Activation Script

Your virtual environment's path or your python version will differ. Ensure you use the correct path for your venv name and Python version in the following commands

Navigate to your env-package path: 

cd ~/path/to/your/env-package
Use the next command to get the absolute path of your current file: 
pwd

env-package-path environment package path

navigate to your virtual environment activate file: 

cd ~/path/to/your/activate_file
open the activate file using a text editor: 
gedit activate

open-activate-file Open activate file

Add the env-package path to your activate file: 

export PYTHONPATH=${PYTHONPATH}:/path-to-your-env/lib/python3.10/site-packages

edit-activate-file Edit activate file

Activate your Python virtual environment: 

source venv/bin/activate

To exit your virtual virtual environment type: 

deactivate

Install the necessary Python modules for the application: 

pip install -r requirements -v

Compile the packages: 

colcon build

Use colcon build only within your ros workspace

Activate the environment you just compiled: 

source install/setup.bash

Run the app: 

ros2 launch drone_altitude_bringup drone_altitude.launch.xml

Troubleshooting

Tello Connection Problems

Issue: Cannot connect ro Tello drone

Check WiFi connection: 

nmcli device wifi list
nmcli connection show
Verify Tello WiFi is available: 
sudo iwlist scan | grep -i tello
Restart network manager: 
sudo systemctl restart NetworkManager

Module problems

Issue: "ModuleNotFoundError: No module named 'matplotlib.tri.triangulation'"

Uninstall matplotlib in your virtual environment: 

pip uninstall matplotlib -y