as2_platform_crazyswarm

ROS 2 platform plugin that bridges Aerostack2 with Crazyswarm2, enabling single-drone and swarm control of Crazyflie UAVs through the AS2 framework.

Architecture

Aerostack2 (missions, planners, controllers)
        │
        ▼
as2_platform_crazyswarm   ←─── this package
        │
        ▼
Crazyswarm2 server  (crazyflie_server node)
        │
        ▼
Crazyflie hardware  (via USB Crazyradio PA)

The platform node subscribes to AS2 control commands and translates them to Crazyswarm2 topics/services. Sensor data flows in the opposite direction: Crazyswarm2 publishes odometry, status, and IMU; this node reformats and re-publishes them as AS2 sensor streams.

For motion-capture setups an external mocap bridge node is also required — it translates rigid-body poses from your mocap system into the /poses topic that Crazyswarm2 consumes to feed the drone's Kalman filter.

Requirements

Minimal ROS 2 package set

The minimum set of ROS 2 packages required to build and run this platform is:

Package	Source repo	How to get
`crazyflie_server_py`	Crazyswarm2	build from source (no apt package)
`crazyflie_interfaces`	Crazyswarm2	build from source (no apt package)
`motion_capture_tracking_interfaces`	motion_capture_tracking	build from source (no apt package)
`as2_platform_crazyswarm`	this repo	build from source

crazyflie_server_py and crazyflie_interfaces both live inside the crazyswarm2 repository — clone the whole repo and colcon will build both packages from it. None of these four packages are available via apt.

All other items below are either transitive dependencies pulled in by these packages or optional system libraries.

Full dependency list

Dependency	Notes
ROS 2 Humble or later	Tested on Humble
Aerostack2	`as2_core`, `as2_msgs`
Crazyswarm2	`crazyflie_interfaces`, `crazyflie_server_py`
motion_capture_tracking	`motion_capture_tracking_interfaces`
cflib (`pip install cflib`)	Crazyflie Python driver, required by `crazyflie_server_py`
transforms3d (`apt install python3-transforms3d` or `pip install transforms3d`)	Rotation math used by `crazyflie_server_py`
ros-humble-tf-transformations (`apt install ros-humble-tf-transformations`)	ROS 2 TF transformation utilities
Eigen3	Standard system package (`apt install libeigen3-dev`)
Crazyflie firmware 2026.04 or later	Earlier firmware causes EKF instability

Installation

1. Install ROS 2

Follow the official instructions for ROS 2 Humble (or later). Make sure ros-humble-desktop and python3-colcon-common-extensions are installed.

2. Install Aerostack2

sudo apt install ros-humble-as2-core ros-humble-as2-msgs

Or build from source:

mkdir -p ~/crazyflie_ws/src && cd ~/crazyflie_ws/src
git clone https://github.com/aerostack2/aerostack2.git

3. Install Crazyswarm2 and motion_capture_tracking

Crazyswarm2 and its motion_capture_tracking dependency are not on apt — clone both into your workspace:

cd ~/crazyflie_ws/src
git clone https://github.com/IMRCLab/crazyswarm2.git
git clone https://github.com/IMRCLab/motion_capture_tracking.git

Install the Crazyflie Python driver (cflib) and transforms3d, which are required by the Crazyswarm2 Python server:

pip install cflib transforms3d

4. Build the required source packages

crazyflie_interfaces, crazyflie_server_py, and motion_capture_tracking_interfaces are not available via apt and must be compiled from the repos cloned above:

cd ~/crazyflie_ws
colcon build --packages-select crazyflie_server_py
source install/setup.bash

5. Set up Crazyradio USB permissions

The Crazyradio PA needs a udev rule so it is accessible without root:

# Download and install the udev rule from the cflib repo
sudo curl -fsSL https://raw.githubusercontent.com/bitcraze/crazyflie-lib-python/master/udev/99-bitcraze.rules \
    -o /etc/udev/rules.d/99-bitcraze.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

Log out and back in (or run sudo usermod -aG plugdev $USER) for the rule to take effect.

6. Clone this package

cd ~/crazyflie_ws/src
git clone https://github.com/aerostack2/as2_platform_crazyswarm.git

7. Install remaining system dependencies

cd ~/crazyflie_ws
rosdep install --from-paths src --ignore-src -r -y

8. Build

colcon build --packages-up-to as2_platform_crazyswarm
source install/setup.bash

Project config files

In a real project you maintain two config files. This package only provides default templates — in practice you always pass your own files via launch arguments.

`config/config.yaml` — master AS2 config

This is the single file that every AS2 node in your project reads. The platform node reads only the cf_name and mocap_id fields from each drone's section; other fields are consumed by the state estimator, motion controller, and behavior nodes.

# Global defaults for all nodes
/**:
  platform:
    ros__parameters:
      cmd_freq: 100.0
      info_freq: 10.0
      connection_timeout: 1.0
      multi_ranger_deck: false

# One block per drone — key is the AS2 namespace
drone0:
  platform:
    ros__parameters:
      cf_name: "cf1"    # must match a key under robots: in crazyflies.yaml
      mocap_id: "34"    # rigid-body streaming ID in Motive (only needed with mocap)

drone1:
  platform:
    ros__parameters:
      cf_name: "cf2"
      mocap_id: "35"

The swarm launch discovers drone namespaces by reading every top-level key in this file that is not /**.

`config/crazyflies.yaml` — Crazyswarm2 drone registry

This file is read by the Crazyswarm2 server, not by this platform node. It maps each cf_name to its radio URI and configures firmware logging.

fileversion: 3

robots:
  cf1:
    enabled: true
    uri: radio://0/80/2M/E7E7E7E701   # Crazyradio address printed on the drone
    initial_position: [0.0, 0.0, 0.0]
    type: cf21
    firmware_logging:
      enabled: true
      default_topics:
        odom:
          frequency: 50   # Hz — pose + velocity consumed by this platform
        status:
          frequency: 10   # Hz — battery voltage consumed by this platform
      custom_topics:
        imu:
          frequency: 100  # Hz — acc (G) and gyro (deg/s) consumed by this platform
          vars: [acc.x, acc.y, acc.z, gyro.x, gyro.y, gyro.z]

Per-drone identity chain

Each drone has three identifiers that must be kept consistent across the two config files above:

Identifier	What it is	Where it is set	Consumed by
`mocap_id`	Streaming ID of the rigid body in Motive (e.g. `"34"`)	`config.yaml` per-drone block	`mocap_bridge` node
`cf_name`	Logical name in Crazyswarm2 (e.g. `"cf1"`)	`config.yaml` per-drone block and `crazyflies.yaml` robot key	This platform node + Crazyswarm2 server
Radio URI	Hardware address of the Crazyradio link	`crazyflies.yaml` under `robots.<cf_name>.uri`	Crazyswarm2 server

The full chain for one drone:

OptiTrack Motive         config.yaml                      crazyflies.yaml
────────────────         ───────────                      ───────────────
rigid body "34" ─────▶  drone0:                          robots:
                           platform:                        cf1:
                             cf_name: "cf1"  ────────────▶    uri: radio://0/80/2M/E7E7E7E701 ──▶ hardware
                             mocap_id: "34"

When you add or swap a drone, update both files in sync:

Assign a rigid-body streaming ID in Motive and note it as mocap_id.
Add the drone to crazyflies.yaml with its cf_name and radio URI.
Add the drone namespace to config.yaml with matching cf_name and mocap_id.

Usage — single drone

Step 1 — Configure `crazyflies.yaml`

Add your drone with its radio URI and the required firmware logging (see template above).

Step 2 — Start the Crazyswarm2 server

ros2 launch crazyflie launch.py

Step 3 — Launch the platform

ros2 launch as2_platform_crazyswarm crazyswarm_launch.py \
    namespace:=drone0 \
    cf_name:=cf1

cf_name must match the key in crazyflies.yaml. If omitted it defaults to namespace.

Usage — swarm

Step 1 — Configure both files

Add all drones to crazyflies.yaml and to your project config.yaml.

Step 2 — Start the Crazyswarm2 server

Without mocap:

ros2 launch crazyflie launch.py

With mocap (also starts the mocap_bridge node):

ros2 launch as2_platform_crazyswarm crazyswarm_server.launch.py \
    mocap:=true \
    mocap_config_file:=/path/to/your/config.yaml

Step 3 — Launch the swarm platform

ros2 launch as2_platform_crazyswarm crazyswarm_swarm_launch.py \
    swarm_config_file:=config/config.yaml

One CrazyswarmPlatform node is spawned per drone namespace found in config.yaml. The /** block provides shared defaults; per-drone blocks provide cf_name (and optionally mocap_id).

Motion capture setup

The mocap_bridge node is bundled in this package (as2_platform_crazyswarm). It translates rigid-body poses from your mocap system into the /poses topic that Crazyswarm2 uses to feed each drone's Kalman filter.

It subscribes to /mocap/rigid_bodies (mocap4r2_msgs/RigidBodies) and republishes on /poses (motion_capture_tracking_interfaces/NamedPoseArray). At startup it reads the file passed via mocap_config_file, building a mocap_id → cf_name mapping from each drone's platform.ros__parameters block. Rigid bodies whose streaming ID is not in the map are forwarded with their original name unchanged.

Launch it together with the Crazyswarm2 server via crazyswarm_server.launch.py:

ros2 launch as2_platform_crazyswarm crazyswarm_server.launch.py \
    mocap:=true \
    mocap_config_file:=/path/to/your/config.yaml

The mocap_bridge must receive poses at 100 Hz or faster — the Crazyswarm2 server subscribes to /poses with a 100 Hz QoS deadline.

Platform parameters reference

These parameters live under <namespace>.platform.ros__parameters in your config.yaml (or in the package's config/platform_config_file.yaml for the single-drone launch).

Parameter	Type	Default	Description
`cf_name`	`string`	namespace (no `/`)	Crazyswarm2 robot name. Must match a key under `robots:` in `crazyflies.yaml`.
`mocap_id`	`string`	—	Rigid-body streaming ID in Motive. Only read by the `mocap_bridge` node.
`cmd_freq`	`double`	`100.0`	Rate (Hz) at which command setpoints are sent to Crazyswarm2.
`info_freq`	`double`	`10.0`	Rate (Hz) at which platform info (state, control mode) is published.
`connection_timeout`	`double`	`1.0`	Seconds without an odometry message before the drone is declared disconnected.
`multi_ranger_deck`	`bool`	`false`	Set to `true` if a Multi-ranger deck is mounted. Enables the LaserScan sensor stream.

Launch arguments

`crazyswarm_launch.py` — single drone

Argument	Default	Description
`namespace`	`drone0`	AS2 namespace for this drone
`cf_name`	`""` (→ namespace)	Crazyswarm2 robot name
`control_modes_file`	package default	Path to `control_modes.yaml`
`platform_config_file`	package default	Path to `platform_config_file.yaml`

`crazyswarm_swarm_launch.py` — swarm

Argument	Default	Description
`swarm_config_file`	package default	Path to the project `config.yaml` (or any YAML with the same structure)
`control_modes_file`	package default	Path to `control_modes.yaml`
`platform_config_file`	package default	Path to `platform_config_file.yaml` (provides shared defaults)

`crazyswarm_server.launch.py` — Crazyswarm2 server (+ optional mocap bridge)

Argument	Default	Description
`crazyflies_yaml_file`	`config/crazyflies.yaml`	Path to the Crazyswarm2 drone registry YAML
`server_yaml_file`	`config/crazyswarm_server.yaml`	Path to the crazyflie server defaults YAML
`urdf_file`	crazyswarm2 package URDF	Path to the Crazyflie URDF description
`mocap`	`false`	Set to `true` to also launch the `mocap_bridge` node
`mocap_config_file`	`""`	Path to the project `config.yaml` used by `mocap_bridge` to build the `mocap_id → cf_name` mapping. Required when `mocap:=true`.

ROS 2 interface

Topics published by this node (per drone, under `/<namespace>/`)

Topic	Type	Description
`sensor_measurements/imu`	`sensor_msgs/Imu`	IMU (accelerometer + gyroscope)
`sensor_measurements/odom`	`nav_msgs/Odometry`	Odometry from Crazyswarm2
`sensor_measurements/battery`	`sensor_msgs/BatteryState`	Battery voltage
`sensor_measurements/lidar/scan`	`sensor_msgs/LaserScan`	Multi-ranger scan (only if `multi_ranger_deck: true`)
`platform/info`	`as2_msgs/PlatformInfo`	Platform state (armed, offboard, control mode)

Topics subscribed from Crazyswarm2 (under `/<cf_name>/`)

Topic	Type	Description
`/<cf_name>/odom`	`nav_msgs/Odometry`	Odometry from Crazyswarm2 server
`/<cf_name>/status`	`crazyflie_interfaces/Status`	Battery and status from firmware
`/<cf_name>/imu`	`crazyflie_interfaces/LogDataGeneric`	IMU log block from firmware
`/<cf_name>/scan`	`sensor_msgs/LaserScan`	Multi-ranger scan (optional)

Topics published to Crazyswarm2 (under `/<cf_name>/`)

Topic	Type	Description
`/<cf_name>/cmd_position`	`crazyflie_interfaces/Position`	Position + yaw setpoint
`/<cf_name>/cmd_velocity_world`	`crazyflie_interfaces/VelocityWorld`	World-frame velocity setpoint
`/<cf_name>/cmd_hover`	`crazyflie_interfaces/Hover`	Horizontal velocity + altitude hold

Services called (under `/<cf_name>/`)

Service	Type	Description
`/<cf_name>/arm`	`crazyflie_interfaces/Arm`	Arm/disarm the drone
`/<cf_name>/emergency`	`std_srvs/Empty`	Kill switch — cuts motors immediately
`/<cf_name>/notify_setpoints_stop`	`crazyflie_interfaces/NotifySetpointsStop`	Signal end of offboard setpoints

License

BSD-3-Clause. See LICENSE for details.

Name		Name	Last commit message	Last commit date
as2_platform_crazyswarm		as2_platform_crazyswarm
config		config
include/as2_platform_crazyswarm		include/as2_platform_crazyswarm
launch		launch
src		src
CMakeLists.txt		CMakeLists.txt
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
README.md		README.md
package.xml		package.xml

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as2_platform_crazyswarm

Architecture

Requirements

Minimal ROS 2 package set

Full dependency list

Installation

1. Install ROS 2

2. Install Aerostack2

3. Install Crazyswarm2 and motion_capture_tracking

4. Build the required source packages

5. Set up Crazyradio USB permissions

6. Clone this package

7. Install remaining system dependencies

8. Build

Project config files

config/config.yaml — master AS2 config

config/crazyflies.yaml — Crazyswarm2 drone registry

Per-drone identity chain

Usage — single drone

Step 1 — Configure crazyflies.yaml

Step 2 — Start the Crazyswarm2 server

Step 3 — Launch the platform

Usage — swarm

Step 1 — Configure both files

Step 2 — Start the Crazyswarm2 server

Step 3 — Launch the swarm platform

Motion capture setup

Platform parameters reference

Launch arguments

crazyswarm_launch.py — single drone

crazyswarm_swarm_launch.py — swarm

crazyswarm_server.launch.py — Crazyswarm2 server (+ optional mocap bridge)

ROS 2 interface

Topics published by this node (per drone, under /<namespace>/)

Topics subscribed from Crazyswarm2 (under /<cf_name>/)

Topics published to Crazyswarm2 (under /<cf_name>/)

Services called (under /<cf_name>/)

License

About

Resources

Contributing

Stars

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Contributors

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`config/config.yaml` — master AS2 config

`config/crazyflies.yaml` — Crazyswarm2 drone registry

Step 1 — Configure `crazyflies.yaml`

`crazyswarm_launch.py` — single drone

`crazyswarm_swarm_launch.py` — swarm

`crazyswarm_server.launch.py` — Crazyswarm2 server (+ optional mocap bridge)

Topics published by this node (per drone, under `/<namespace>/`)

Topics subscribed from Crazyswarm2 (under `/<cf_name>/`)

Topics published to Crazyswarm2 (under `/<cf_name>/`)

Services called (under `/<cf_name>/`)