CrazySim: A Software-in-the-Loop Simulator for the Crazyflie Nano Quadrotor

This code accompanies the work in the ICRA 2024 submission "CrazySim: A Software-in-the-Loop Simulator for Nano Quadcopter Fleets".

Supported Platforms

This simulator is currently only supported on Ubuntu systems with at least 20.04. This is primarily a requirement from Gazebo Sim. The simulator was built, tested, and verified on 22.04 with Gazebo Garden.

To install this repository use the recursive command as shown below for HTTPS:

git clone https://github.com/gtfactslab/Llanes_ICRA2024.git --recursive

crazyflie-lib-python

cd crazyflie-lib-python
pip install -e .

crazyflie-firmware

The installation instructions and usage are referenced in the documentation file.

Dependencies

Install dependencies using the code below.

pip install Jinja2

Building the code

First install Gazebo Garden from https://gazebosim.org/docs/garden/install_ubuntu

Run the command to build the firmware and Gazebo plugins.

cd crazyflie-firmware
mkdir -p sitl_make/build && cd $_
cmake ..
make all

Crazyswarm2 and MPC code

Make sure you have ROS 2 Humble.

Install the following for Crazyswarm2:

sudo apt install libboost-program-options-dev libusb-1.0-0-dev
pip3 install rowan transforms3d
sudo apt install ros-humble-tf-transformations

If you want to run the MPC code then you will need Acados. Acados can be installed by following their documentation.

Then build the ROS 2 workspace.

cd ros2_ws
colcon build --symlink-install

Configuration

The crazyswarm2 configuration files can be found in

ros2_ws/src/crazyswarm2/crazyflie/config/

The crazyflies.yaml describes the robots currently being used. If a robot is not in the simulator or hardware, then it can be disabled by setting the enabled parameter to false. A more detailed description for crazyswarm2 configurations can be found here.

The main code for the MPC script is in the following:

ros2_ws/crazyflie_mpc/crazyflie_mpc/crazyflie_multiagent_mpc.py

The trajectory type can be changed to a horizontal circle, vertical circle, helix, or a lemniscate trajectory by changing the variable "trajectory_type" in the CrazyflieMPC class.

Usage

Currently, users have to restart Gazebo after each CFLib connect and disconnect cycle. Supporting a restart cycle without restarting Gazebo is on the list of things to do.

Start up SITL

Open a terminal and run

cd crazyflie-firmware

We can then run the firmware instance and spawn the models with Gazebo using a single launch script.

Option 1: Spawning a single crazyflie model with initial position (x = 0, y = 0)

bash tools/crazyflie-simulation/simulator_files/gazebo/launch/sitl_singleagent.sh -m crazyflie -x 0 -y 0

Option 2: Spawning 8 crazyflie models to form a perfect square

bash tools/crazyflie-simulation/simulator_files/gazebo/launch/sitl_multiagent_square.sh -n 8 -m crazyflie

Option 3: Spawning multiple crazyflie models with positions defined in the agents.txt file. New vehicles are defined by adding a new line with comma deliminated initial position x,y.

bash tools/crazyflie-simulation/simulator_files/gazebo/launch/sitl_multiagent_text.sh -m crazyflie

Start Crazyswarm2

Launch the Crazyswarm2 services with CFLib backend.

ros2 launch crazyflie launch.py backend:=cflib

Start MPC code

Run the Crazyflie MPC demonstration with the code below. The argument n_agents can be modified for the number of agents in your environment.

ros2 run crazyflie_mpc crazyflie_multiagent_mpc --n_agents=1

Using the command line publisher we can command all vehicles to take off using MPC.

ros2 topic pub -t 50 -r 50 /all/mpc_takeoff std_msgs/msg/Empty

Using the command line publisher we can command all vehicles to start the trajectory.

ros2 topic pub -t 50 -r 50 /all/mpc_trajectory std_msgs/msg/Empty

Using the command line publisher we can command all vehicles to stop the trajectory and hover.

ros2 topic pub -t 50 -r 50 /all/mpc_hover std_msgs/msg/Empty

We also implemented a MPC land feature, but it's still experimental and may result in crashing the drone.

Fenix0817/Llanes_ICRA2024