This is the code for the 5G RCID of the 5G Hub. All ROS2 nodes and the API code can be found here. The flight computer currently already contains the latest version of the software.

The code for the ROS2 nodes can be found in the src folder (src/)
The code for the API can be found in the api folder (api/)
Further information about how the drone is built and how it works can be found in my report in the docs folder (doc/)

To add new ROS2 functionality, you can edit the code, push to the repository, pull on the flight computer (ubuntu@10.100.0.40, password is raspberrypi) and build the ROS2 workspace again. An example of how to do this is shown below:

# (On your computer) commit changes
git commit -a -m "Added new functionality"
git push
# (On the flight computer) pull changes
cd /home/ubuntu/ros2_ws
git fetch
git pull
# (On the flight computer) build workspace
colcon build --allow-overriding drone_services
# (On the flight computer) source workspace
source install/setup.bash
# (On the flight computer) restart ROS2 nodes
drone_scripts/restart_services.sh

To add new API functionality, you can do the same, but for the code in the api folder. Then, log in on the edge computer and pull the changes. The API is automatically restarted when the code is changed. If you want to manually restart the API, you can do so using the following command:

# (On the edge computer) restart API
sudo systemctl restart webserver

EMERGENCY FORCE STOP

If, for whatever reason, the drone does not respond to the API, you can force stop all nodes on the drone and force it to land through the pixhawk using the following commands:

# on your computer, ssh into the drone
ssh ubuntu@10.100.0.40
# cd into the ROS2 workspace
cd ros2_ws
# stop all ROS2 nodes
drone_scripts/stop_services.sh

Pin layout

A pinout of the raspberry pi can be found here. The connections are visible in the table below:

Raspberry Pi pin	Function	Connected to
2	5V	Power input from PDB
4	5V	Power to relais
6	GND	Ground from PDB
8	UART TX	To RX of Pixhawk TELEM 1
9	GND	Ground to relais
10	UART RX	To TX of Pixhawk TELEM 1
11	GPIO 17	Relais
13	GPIO 27	Relais

Connecting to API

To connect to the API, make sure you are connected to the 5G Hub network. Then, the API is located at http://10.1.1.41:8080/. When the drone is finished booting (the relais is switched on), you can connect to the drone using the Connect button.

Installing API

To be able to run the API, npm and nodejs must be installed:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.3/install.sh | bash
nvm install node
# to be able to run npm and nodejs as sudo, run the following commands:
n=$(which node)
n=${n%/bin/node}
chmod -R 755 $n/bin/* 
sudo cp -r $n/{bin,lib,share} /usr/local

To install the API on a new edge computer, you must first clone this repository. Then you can run the NodeJS webserver using npm. You can do that using the following commands:

git clone https://github.com/etmeddi/5g_drone_ROS2.git
cd 5g_drone_ROS2/api
npm start

Installation on new flight computer

The drone currently has a Raspberry Pi that contains a ROS2 installation. The Raspberry Pi runs Ubuntu 20.04 and ROS 2 Foxy. If you want to install this on a new Pi, you should get Ubuntu Server 20.04, and install ROS2 Foxy on it. Then, you should clone this repository into a ros2_ws folder. You can do that using the following commands:

git clone git@github.com:etmeddi/5g_drone_ROS2.git
mv 5g_drone_ROS2 ros2_ws

After that, to make sure the connection to PX4 works, you should follow the PX4 ROS2 User Guide provided by PX4.

Building PX4 firmware

The RCID uses a custom version of the PX4 firmware to include the battery percentage and CPU load of the flight controller. Before building the firmware, make sure the developer toolchain is set up correctly. To build the firmware, first clone the repository (from the PX4 docs):

# enter home directory
cd
# clone git repository
git clone https://github.com/PX4/PX4-Autopilot.git --recursive

In the PX4 directory, edit the file src/modules/uxrce_dds_client/dds_topics.yaml. Above the line that says subscriptions:, add the following:

  - topic: /fmu/out/battery_status
    type: px4_msgs::msg::BatteryStatus
  - topic: /fmu/out/cpuload
    type: px4_msgs::msg::Cpuload

The file can also be found in this repository at dds_topics.yaml. After changing the file, you can build the firmware using the following command:

# navigate to root of PX4 directory
cd ~/PX4-Autopilot
# build firmware
make px4_fmu-v5_default

The built firmware file will be located at PX4-Autopilot/build/px4_fmu-v4_default/px4_fmu-v4_default.px4. You can then flash this to the flight controller using QGroundControl. Make sure to select the custom firmware option when flashing, and select the built firmware file.

ROS2 nodes overview

An overview of all the ROS2 nodes, services and topics can be found below (also visible in my report)

PX4 parameters

To enable communication with the flight computer, the following parameters should be set in QGroundControl:

Parameter	Value	Function
UXRCE_DDS_CFG	101	run microxrce-dds on TELEM 1
MAV_0_CONFIG	TELEM 4	run mavlink on TELEM 4 because XRCE-DDS runs on TELEM 1
SER_TEL1_BAUD	921600	high baud rate because serial
COM_RC_IN_MODE	4 (Stick input disabled)	allow arming without GPS
COM_RCL_EXCEPT	5	Ignore loss of RC remote signal

Optical flow

The optical flow sensor is a Hex HereFlow PMW3901 and it's connected to the CAN port of the pixhawk. The parameters to enable the optical flow sensor are:

Parameter	Value	Function
EKF2_OF_CTRL	1 (Enabled)	Enable optical flow sensor fusion
UAVCAN_ENABLE	2 (Sensors automatic config)	Enable UAVCAN for sensors
UAVCAN_SUB_FLOW	Enabled	subscribe to optical flow messages
UAVCAN_SUB_GPS	Disabled	subscribe to GPS messages

To reverse this, and be able to use GPS, the parameters should be:

Parameter	Value	Function
EKF2_OF_CTRL	0 (Disabled)	Disable optical flow sensor fusion
UAVCAN_ENABLE	0 (Disabled)	Disable UAVCAN for sensors
UAVCAN_SUB_FLOW	Disabled	don't subscribe to optical flow messages
UAVCAN_SUB_GPS	Enabled	subscribe to GPS messages

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README.md

5G RCID

5G Remote Controlled Inspection Drone

Table of contents

Introduction