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Drone Control Stack Setup

This section describes the steps followed to install the drone control stack on the onboard computer. This stack is composed of ROS packages which allow the vehicle to be controlled from ROS nodes using the available cpp UAV class. It should be noted that the steps described include everything that is needed to run simulations in adition to controlling the real drone.

Environment Setup

Before installing the ROS packages, it is necessary to create a workspace and install the PX4 firmware (only used for simulations).

  • Creating a catkin workspace 

    mkdir ~/uav/uav_ws/src
cd ~/uav/uav_ws
catkin_make

  • Installing the PX4 firmware 

    cd ~/uav
git clone --recursive https://github.com/PX4/PX4-Autopilot.git
cd PX4-Autopilot
git fetch --all --tags
git checkout v1.12.3 -b latest
git submodule update --init --recursive
make px4_sitl gazebo

Note

While installing the PX4 firmware, some missing packages might need to be installed with pip. If pip is not available it can be installed with sudo apt install python3-pip.

  • In order not to pollute the bashrc profile, a script was created to load the needed environment variables 

    cd ~/uav
touch setup.bash

  • Contents of the setup.bash file 

    source ~/uav/uav_ws/devel/setup.bash

export CATKIN_WORKSPACE=~/uav/uav_ws

export GAZEBO_PLUGIN_PATH=$GAZEBO_PLUGIN_PATH:/home/jetson/uav/PX4-Autopilot/build_gazebo
export GAZEBO_MODEL_PATH=$GAZEBO_MODEL_PATH:/home/jetson/uav/PX4-Autopilot/Tools/sitl_gazebo/models

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/jetson/uav/PX4-Autopilot/build_gazebo
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:/home/jetson/uav/PX4-Autopilot:/home/jetson/uav/PX4-Autopilot/Tools/sitl_gazebo

source /home/jetson/uav/PX4-Autopilot/Tools/setup_gazebo.bash /home/jetson/uav/PX4-Autopilot /home/jetson/uav/PX4-Autopilot/build/px4_sitl_default

Control Stack Overview

Now that the environment is prepared, the code stack can be installed inside the created workspace. Below is a tree view of all the packages included in the stack. The packages listed here are available in this repository.

src/
├── drone_bringup
├── drone_gazebo
│   ├── drone_description
│   └── drone_worlds
├── drone_launch
└── drone_library
    ├── drone_gimmicks_library
    ├── drone_utils_cpp
    └── mavros_cpp

Simulation flow

graph TD
  A(<b>simulator_bringup.launch</b> <br> drone_launch) --> B(<b>vehicle_bringup.launch</b> <br> drone_launch);
  A --> C(<b>empty_world.launch</b> <br> gazebo_ros);
  A -. simulator_bringup_rviz.launch .-> G(<b>rviz</b> <br> rviz);
  B --> D(<b>single_vehicle_spawn.launch</b> <br> drone_launch);
  B --> E(<b>px4.launch</b> <br> mavros);
  B --> F(<b>drone_sim.launch</b> <br> drone_bringup);

Real mission flow

graph TD
  A(<b>real_bringup_rviz.launch</b> <br> drone_launch) --> B(<b>px4.launch</b> <br> mavros);
  A --> C(<b>drone_sim.launch</b> <br> drone_bringup);
  A --> G(<b>rviz</b> <br> rviz);

ROS Packages Overview

drone_bringup

The drone_sim.launch file loads the vehicle and main algorithm parameters and calls the ROS node that has the mission to be carried out.

src/drone_bringup/
├── CMakeLists.txt
├── config
│   └── simulation
│       └── iris
│           └── config.yaml
├── launch
│   └── drone_sim.launch
└── package.xml

drone_description

The drone_description package contains the Gazebo models for the vehicles used.

src/drone_gazebo/drone_description/
├── CMakeLists.txt
├── models
│   └── iris
│       ├── iris.sdf.jinja
│       ├── iris.urdf
│       ├── meshes
│       │   ├── iris_prop_ccw.dae
│       │   ├── iris_prop_cw.dae
│       │   └── iris.stl
│       └── model.config
├── package.xml
└── scripts
    ├── jinja_gen.py
    ├── names.py
    ├── schema_download.bash
    ├── substitution_args.py
    └── validate_sdf.bash

drone_worlds

The drone_worlds package contains the world files that can be used during simulations in Gzaebo.

src/drone_gazebo/drone_worlds/
├── CMakeLists.txt
├── package.xml
└── worlds
    ├── baylands.world
    ├── boat.world
    ├── empty.world
    ├── hippocampus.world
    ├── hitl_iris.world
    ├── hitl_standard_vtol.world
    ├── iris_irlock.world
    ├── ksql_airport.world
    ├── mcmillan_airfield.world
    ├── ocean.world
    ├── sonoma_raceway.world
    ├── typhoon_h480.world
    ├── uuv_bluerov2_heavy.world
    ├── uuv_hippocampus.world
    ├── warehouse.world
    ├── windy.world
    └── yosemite.world

drone_launch

The drone_launch package contains several launch files that are used to run simulations and to run missions with the real drone.

src/drone_launch/
├── CMakeLists.txt
├── launch
│   ├── real_bringup_rviz.launch
│   ├── rvizcfg.rviz
│   ├── simulator_bringup.launch
│   ├── simulator_bringup_rviz.launch
│   ├── single_vehicle_spawn.launch
│   └── vehicle_bringup.launch
└── package.xml

drone_gimmicks_library

The drone_gimmicks_library package contains some useful macros to reduce the complexity of some common ROS operations like getting parameters.

src/drone_library/drone_gimmicks_library/
├── CMakeLists.txt
├── include
│   └── drone_gimmicks_library
│       └── DroneGimmicks.h
├── package.xml
└── src
    └── DroneGimmicks.cpp

drone_utils_cpp

The drone_utils_cpp package contains some useful functions while working with drones, like converting between different coordinate frames and normalizing thrust values.

src/drone_library/drone_utils_cpp/
├── CMakeLists.txt
├── doc
│   └── README.md
├── include
│   └── drone_utils_cpp
│       ├── DroneInfo.h
│       ├── DroneStatus.h
│       └── Utils.h
├── package.xml
└── src
    └── Utils.cpp

mavros_cpp

The mavros_cpp package contains the main class (UAV) which is used to control the drone as well as to get telemetry data.

src/drone_library/mavros_cpp/
├── CMakeLists.txt
├── doc
│   └── README.md
├── include
│   └── mavros_cpp
│       ├── Actuators.h
│       ├── EKF.h
│       ├── Sensors.h
│       └── UAV.h
├── package.xml
└── src
    ├── offboard.cpp
    ├── telemetry.cpp
    └── UAV.cpp

Simulation example

After installing the code stack the provided lissajous example package can be executed in simulation. The drone_sim.launch file in the drone_bringup package should contain a call to the lissajous ROS node like so - <node pkg="lissajous" type="lissajous_node" name="lissajous" respawn="false" output="screen"/>.

  1. Build the workspace 

    cd ~/uav/uav_ws
catkin_make

  2. Source the provided bash script 

    cd ~/uav
source setup.bash

  3. Run the simulation 

    roslaunch drone_launch simulator_bringup.launch

    Lissajous Gazebo Simulation