CrazyS is an extension of the ROS package RotorS, aimed to modeling, developing and integrating the Crazyflie 2.0 nano-quadcopter in the physics based simulation environment Gazebo. The contribution can be also considered as a reference guide for expanding the RotorS functionalities in the UAVs field, by facilitating the integration of new aircrafts.

Such simulation platform allows to understand quickly the behavior of the flight control system by comparing and evaluating different indoor and outdoor scenarios, with a details level quite close to reality. The proposed extension expands RotorS capabilities by considering the Crazyflie 2.0 physical model and its flight control system, as well (the 2018.01.1 firware release).

A simple case study is considered (crazyflie2_hovering_example.launch) in order to show how the package works and the validity of the employed dynamical model together the control architecture of the quadcopter.

The code is released under Apache license, thus making it available for scientific and educational activities.

The platform has been developed by using Ubuntu 16.04 and the Kinetic Kame version of ROS. Although the platform is fully compatible with Indigo Igloo version of ROS and Ubuntu 14.04, such configuration is not recommended since the ROS support will close in April 2019.

Below we provide the instructions necessary for getting started. See CrazyS' wiki for more instructions and examples.

If you are using this simulator within the research for your publication, please take a look at the Publications page. The page contains core papers and all linked works (using the platform).

1. Install and initialize ROS kinetic desktop full, additional ROS packages, catkin-tools, and wstool:

$ sudo sh -c ’echo "deb https://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list’
$ sudo apt-key adv --keyserver hkp:https://ha.pool.skskeyservers.net:80 --recv-key 421C365BD9FF1F717815A3895523BAEEB01FA116
$ sudo apt-get update
$ sudo apt-get install ros-kinetic-desktop-full ros-kinetic-joy ros-kinetic-octomap-ros ros-kinetic-mavlink python-catkin-tools protobuf-compiler libgoogle-glog-dev ros-kinetic-control-toolbox
$ sudo rosdep init
$ rosdep update
$ echo "source /opt/ros/kinetic/setup.bash" >> ~/.bashrc
$ source ~/.bashrc
$ sudo apt-get install python-rosinstall pythonrosinstall-
generator python-wstool build-essential

2. If you don't have ROS workspace yet you can do so by

$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws/src
$ catkin_init_workspace  # initialize your catkin workspace
$ catkin init
$ git clone https://github.com/gsilano/CrazyS.git
$ git clone https://github.com/gsilano/mav_comm.git
$ cd ~/catkin_ws/src/mav_comm & git checkout crazys
$ rosdep update
$ cd ~/catkin_ws
$ rosdep install --from-paths src -i
$ catkin build

Note On OS X you need to install yaml-cpp using Homebrew brew install yaml-cpp.

3. Build your workspace with python_catkin_tools (therefore you need python_catkin_tools)

$ cd ~/catkin_ws/
$ catkin build

4. Add sourcing to your .bashrc file

$ echo "source ~/catkin_ws/devel/setup.bash" >> ~/.bashrc
$ source ~/.bashrc

1. Install and initialize ROS indigo desktop full, additional ROS packages, catkin-tools, and wstool:

$ sudo sh -c ’echo "deb https://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list’
$ sudo apt-key adv --keyserver hkp:https://ha.pool.skskeyservers.net:80 --recv-key 421C365BD9FF1F717815A3895523BAEEB01FA116
$ sudo apt-get update
$ sudo apt-get install ros-indigo-desktop-full ros-indigo-joy ros-indigo-octomap-ros python-wstool python-catkin-tools protobuf compiler libgoogle-glog-dev
$ sudo rosdep init
$ rosdep update
$ echo "source /opt/ros/indigo/setup.bash" >> ~/.bashrc
$ source ~/.bashrc
$ sudo apt-get install python-rosinstall

2. If you don't have ROS workspace yet you can do so by

$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws/src
$ catkin_init_workspace  # initialize your catkin workspace
$ catkin init

Note for setups with multiple workspaces please refer to the official documentation by replacing rosws by wstool.

3. Get the simulator and additional dependencies

$ cd ~/catkin_ws/src
$ git clone https://github.com/gsilano/CrazyS.git
$ git clone https://github.com/gsilano/mav_comm.git
$ cd ~/catkin_ws/src/mav_comm & git checkout crazys
$ rosdep update
$ cd ~/catkin_ws
$ rosdep install --from-paths src -i

Note On OS X you need to install yaml-cpp using Homebrew brew install yaml-cpp.

Note if you want to use wstool you can replace the above commands with wstool set --git local_repo_name [email protected]:organization/repo_name.git Note if you want to build and use the gazebo_mavlink_interface plugin you have to get MAVROS as an additional dependency from link below. Follow the installation instructions provided there and build all of its packages prior to building the rest of your workspace. https://github.com/mavlink/mavros

4. Build your workspace with python_catkin_tools (therefore you need python_catkin_tools)

$ cd ~/catkin_ws/
$ catkin init  # If you haven't done this before.
$ catkin build

Note if you are getting errors related to "future" package, you may need python future: sudo apt-get install python-pip pip install --upgrade pip pip install future

5. Add sourcing to your .bashrc file

$ echo "source ~/catkin_ws/devel/setup.bash" >> ~/.bashrc
$ source ~/.bashrc

Launching the simulation is quite simple, so as customizing it: it is enough to run in a terminal the command

$ roslaunch rotors_gazebo crazyflie2_hovering_example.launch

Note The first run of gazebo might take considerably long, as it will download some models from an online database. To avoid any problems when starting the simulation for the first time, you may run the gazebo command in the terminal line.

By default the state estimator is disabled since on-board Crazyflie's sensors are replaced by the odometry one. For running the simulation by taking into account the Crazyflie's IMU and the complementary filter, it is enough to give a command that turns on the flag enable state estimator:

$ roslaunch rotors_gazebo crazyflie2_hovering_example.launch enable_state_estimator:=true

The visual outcome will see the nano-quadcopter taking off after 5s (time after which the hovering example node publishes the trajectory to follow) and flying one meter above the ground, at the same time keeping near to zero the position components along x and y-axis.

The whole process is the following: the desired trajectory coordinates (x_r, y_r, z_r and \psi_r) are published by the hovering_example node on the topic command/trajectory, to whom the position_controller node (i.e., the Crazyflie controller) is subscribed. The drone state (odometry_sensor1/odometry topic) and the references are used to run the control strategy designed for the position tracking. The outputs of the control algorithm consist into the actuation commands (\omega_1, \omega_2, \omega_3 and \omega_4) sent to Gazebo (command/motor_speed) for the physical simulation and the corresponding graphical rendering, so to visually update the aircraft position and orientation. When the state estimator is turned off, the drone orientation (\phi_k, \theta_k and \psi_k) and angular velocities (p_k, q_k and r_k) published on the topic odometry are replaced by the ideal values coming from the odometry sensor.

There are some basic launch files where you can load the different multicopters with additional sensors. They can all be found in ~/catkin_ws/src/CrazyS/rotors_gazebo/launch. Suche scenarios are better explained in the RotorS repository.

The world_name argument looks for a .world file with a corresponding name in ~/catkin_ws/src/CrazyS/rotors_gazebo/worlds. By default, all launch files, with the exception of those that have the world name explicitly included in the file name, use the empty world described in basic.world.

At a minimum, Gazebo v2.x is required (which is installed by default with ROS Indigo). However, it is recommended to install at least Gazebo v5.x for full functionlity, as there are the following limitations:

1. iris.sdf can only be generated with Gazebo >= v3.0, as it requires use of the gz sdf ... tool. If this requirement is not met, you will not be able to use the Iris MAV in any of the simulations.
2. The Gazebo plugins GazeboGeotaggedImagesPlugin, LidarPlugin and the LiftDragPlugin all require Gazebo >= v5.0, and will not be built if this requirement is not met.

Please report bugs and request features by using the Issue Tracker. Furthermore, please see the Contributing.md file if you plan to help us to improve CrazyS features.

In this section a video providing the effectiveness of the platform and how it works is reported. Further videos can be found in the related YouTube channel. Have fun! :)