- tutorials/demos/crazyflie_demo

This demo aims to expose a **micro-ROS** use case. It runs on a pair of embedded devices:

a [**Crazyflie 2.1**](https://www.bitcraze.io/crazyflie-2-1/) drone, used as a user controller,

and a [**Kobuki Turtlebot 2**](https://www.turtlebot.com/turtlebot2/) as a mobile and controlled device.


Both of them rely on **micro-ROS** publication and subscription mechanisms and use an underlying [**Micro XRCE-DSS client**](https://micro-xrce-dds.readthedocs.io/en/latest/).

This demo also includes conventional ROS 2 tooling as a demonstration of integration with **ROS 2**. We use Gazebo, RVIZ and simple ROS 2 nodes (aka **external nodes**) acting as data converters.

This demo was developed taking as base the [Kobuki demo](/docs/tutorials/demos/kobuki_demo).

- [Installation](#installation)

- [Install external ROS 2 nodes](#install-external-ros-2-nodes)

- [Build and flash Crazyflie 2.1 firmware](#build-and-flash-crazyflie-21-firmware)

- [Install Crazyflie Client + Bridge](#install-crazyflie-client--bridge)

- [Build and flash Kobuki Turtlebot 2 firmware](#build-and-flash-kobuki-turtlebot-2-firmware)

- [Usage](#usage)

- [Run Kobuki Turtlebot 2 Node](#run-kobuki-turtlebot-2-node)

- [Run Crazyflie 2.1 Node](#run-crazyflie-21-node)

- [Run external ROS 2 nodes](#run-external-ros-2-nodes)

- [Run RVIZ visualizers](#run-rviz-visualizers)

The proposed demo is composed of different kind of messages and topics.

The **Crazyflie 2.1** drone relies on [ST STM32F405](https://www.st.com/en/microcontrollers-microprocessors/stm32f405-415.html) MCU running **[FreeRTOS](https://www.freertos.org/)**. Using the RTOS capabilities and the integrated radio communication device, the drone can run a node that publishes:

- its own relative position as a 3D vector (X, Y and Z) using a *geometry_msg/Point32* message type on */drone/odometry* topic.

- its own attitude as a 3D vector (pitch, roll and yaw) using a *geometry_msg/Point32* message type on */drone/attitude* topic.

The **Kobuki Turtlebot 2** robot is controlled using a UART protocol through a custom DB25 connector. The micro-ROS node runs on an Olimex STM32-E407 board attached to that UART port. This hardware features a [ST STM32F407](https://www.st.com/en/microcontrollers-microprocessors/stm32f407-417.html) MCU running **[Nuttx](https://nuttx.org/)** RTOS. In the same way, this node can communicate with the robot (UART) and with the ROS2 world (integrated Ethernet). Its used topics are:

- a subscription on */cmd_vel* topic (*geometry_msg/Twist* message type) to receive the controlling angular and linear velocity.

- a publication on */robot_pose* topic (*geometry_msg/Vector3* message type) which includes X position, Y position and robot yaw.

The **external ROS 2 nodes** are rclpy tools with some different functionalities:

- *attitude_to_vel.py*

- Converts Crazyflie */drone/attitude* to Kobuki Turtlebot 2 */cmd_vel* so that drone pitch is mapped to robot linear velocity and drone roll to angular valocity.

- Converts Crazyflie publications on */drone/attitude* and */drone/attitude* topics to *tf2_msgs/TFMessage* messages (required by RVIZ visualizer)

- *odom_to_tf.py*

- Converts Kobuki Turtlebot 2 publications on */robot_pose* topic to *tf2_msgs/TFMessage* messages (required by RVIZ visualizer).

The following image shows the described setup.


This setup uses the following hardware:

| Item | |

|---------------|----------------------------------------------------------|

| Kobuki Turtlebot 2 | [Link](https://www.turtlebot.com/turtlebot2/) |

| Olimex STM32-E407 | [Link](https://www.olimex.com/Products/ARM/ST/STM32-E407/open-source-hardware) |

| Olimex ARM-USB-TINY-H | [Link](https://www.olimex.com/Products/ARM/JTAG/ARM-USB-TINY-H/) |

| Crazyflie 2.1 | [Link](https://store.bitcraze.io/products/crazyflie-2-1) |

| Flow Desk v2 | [Link](https://store.bitcraze.io/collections/decks/products/flow-deck-v2) |

| Debug adapter | [Link](https://store.bitcraze.io/collections/accessories/products/debug-adapter) |

| Crazyradio PA 2.4 GHz USB dongle | [Link](https://store.bitcraze.io/collections/accessories/products/crazyradio-pa) |

| Additional battery + charger (optional) | [Link](https://store.bitcraze.io/collections/accessories/products/240mah-lipo-battery-including-500ma-usb-charger) |

[Install Micro XCRE-DDS](https://micro-xrce-dds.readthedocs.io/en/latest/installation.html). Recommended procedure:

git clone https://github.com/eProsima/Micro-XRCE-DDS.git -b v1.1.0

cd Micro-XRCE-DDS

mkdir build && cd build

cmake ..

make

sudo make install

Create a workspace folder for this demo:

mkdir -p crazyflie_demo/src

cd crazyflie_demo

Clone this repo:

git clone --single-branch --branch crazyflie_demo https://github.com/micro-ROS/micro-ROS_kobuki_demo src

[Install Gazebo](http://gazebosim.org/tutorials?tut=install_ubuntu&cat=install#InstallGazebousingUbuntupackages). Recommended procedure:

curl -sSL http://get.gazebosim.org | sh

[Install gazebo_ros_pkgs (ROS 2)](http://gazebosim.org/tutorials?tut=ros2_installing&cat=connect_ros). Recommended procedure:

source /opt/ros/dashing/setup.bash

wget https://bitbucket.org/api/2.0/snippets/chapulina/geRKyA/f02dcd15c2c3b83b2d6aac00afe281162800da74/files/ros2.yaml

vcs import src < ros2.yaml

rosdep update && rosdep install --from-paths src --ignore-src -r -y

rm ros2.yaml

Build the project:

source /opt/ros/dashing/setup.bash

rosdep update && rosdep install --from-paths src --ignore-src -r -y

colcon build --symlink-install

Install the toolchain:

sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa

sudo apt-get update

sudo apt install gcc-arm-embedded dfu-util

Download and build the **Crazyflie 2.1** firmware repository:

mkdir crazyflie_firmware

git clone https://github.com/eProsima/crazyflie-firmware -b crazyflie_demo

cd crazyflie_firmware

git submodule init

git submodule update

make PLATFORM=cf2

Unplug the **Crazyflie 2.1** battery

Push the reset button while connecting the USB power supply.

The top-left blue LED blinks, first slowly and after 4 seconds sightly faster, now it is in DFU programming mode. Check it with `lsusb`:

Bus 001 Device 051: ID 0483:df11 STMicroelectronics STM Device in DFU Mode

Flash the device:

sudo dfu-util -d 0483:df11 -a 0 -s 0x08000000 -D cf2.bin

Unplug and plug the **Crazyflie 2.1** power to exit DFU mode.

Install dependencies:

Fix permissions for the Crazyradio PA 2.4 GHz USB dongle (restart required for apply changes):

Clone the repo dependencies:

Create a workspace for building **micro-ROS**:

Build **micro-ROS Agent**:

Install tools:

Build Olimex STM32-E407 firmware:

```

Connect Olimex ARM-USB-TINY-H JTAG debugger to Olimex STM32-E407 and flash the board:

After installation, the following packages should be present in your system:

Make sure that all ROS 2 or micro-ROS nodes created along with the following steps **can reach each other using its network interfaces**.

TODO: Explain data and power connections between Kobuki Turtlebot 2, Olimex STM32-E407 and MiniRouter.

Run the **micro-ROS Agent**:

**micro-ROS Agent** should receive an incoming client connection and */robot_pose* topic should be published. Check it with `ros2 topic echo /robot_pose`

Connect Crazyradio PA 2.4 GHz USB dongle and turn on Crazyflie 2.1 drone.

Run the Crazyflie Client + Bridge:

This command should open the Crazyflie Client and print a serial device path in the terminal (something like /dev/pts/0).

Run (in another prompt) a **Micro XRCE-DDS Agent**:

**Micro XRCE-DDS Agent** should receive an incoming client connection and */drone/attitude* and */drone/position* topics should be published. Check it with `ros2 topic echo /drone/attitude` and `ros2 topic echo /drone/position`

Run commands:

Topic */cmd_vel* should be published, and the **Kobuki Turtlebot 2** should start moving. Check it with `ros2 topic echo /cmd_vel`

Run complete visualizer:

RVIZ windows should be open, and a Crazyflie 2.1 drone model should represent the drone attitude and position along with a historic path.

Run attitude visualizer:

RVIZ windows should be open and a Crazyflie 2.1 drone model should represent **only** the drone attitude.

WIP