Building and Installing FastRTPS for ROS2 communication to FMU

FastRTPS and the microRTPS Agent

FastRTPS and the microRTPS agent are needed on NavQ in order to bridge uORB topics from PX4 to ROS2 on NavQ over a UART or UDP connection. Follow the guide below to build and install these packages.

NOTE: FastRTPS and PX4 ROS Com work differently from MAVROS (ROS1). PX4 ROS Com subscribes to uORB topics rather than MAVLINK messages. See below for a diagram of how microRTPS and PX4 ROS Com works.

Follow the link below for more details on microRTPS and PX4 ROS Com:

RTPS/DDS Interface: PX4-Fast RTPS(DDS) Bridge | PX4 User Guide

Installing FastRTPS and PX4 ROS Com on NavQ

Prerequisites

~$ sudo apt update
~$ sudo apt install cmake python3-pip gradle python3-colcon-common-extensions gradle
~$ pip3 install --user pyros-genmsg

FastRTPS installation

First, we will install the FastRTPS project from eProsima. Use the following commands below to do so:

~$ mkdir src && cd src
~/src$ git clone --recursive https://github.com/eProsima/Fast-RTPS.git -b 1.8.x FastRTPS-1.8.2
~/src$ cd FastRTPS-1.8.2
~/src/FastRTPS-1.8.2$ mkdir build
~/src/FastRTPS-1.8.2$ cd build 
~/src/FastRTPS-1.8.2/build$ cmake -DTHIRDPARTY=ON -DSECURITY=ON .. 
~/src/FastRTPS-1.8.2/build$ make 
~/src/FastRTPS-1.8.2/build$ sudo make install

cd ~/src
~/src$ git clone --recursive https://github.com/eProsima/Fast-RTPS-Gen.git -b v1.0.4 Fast-RTPS-Gen
~/src$ cd Fast-RTPS-Gen
~/src/Fast-RTPS-Gen$ unset TERM
~/src/Fast-RTPS-Gen$ ./gradlew assemble
~/src/Fast-RTPS-Gen$ sudo su
~/src/Fast-RTPS-Gen$ unset TERM
~/src/Fast-RTPS-Gen# ./gradlew install
~/src/Fast-RTPS-Gen# exit
~/src/Fast-RTPS-Gen$

px4_ros_com installation

Next, we will build and install the necessary software that will allow us to use ROS2 to communicate with the microRTPS bridge. First, run the following commands:

$ cd ~/
~$ mkdir -p ~/px4_ros_com_ros2/src

~$ git clone https://github.com/PX4/px4_ros_com.git ~/px4_ros_com_ros2/src/px4_ros_com
~$ git clone https://github.com/PX4/px4_msgs.git ~/px4_ros_com_ros2/src/px4_msgs

URGENT: Building px4_ros_com requires a lot of ram. Enabling a swap disk is highly recommended. This will take up 1GB of space on your storage medium.

Run the following commands to enable a 1GB swapfile:

$ sudo fallocate -l 1G /swapfile
$ sudo chmod 600 /swapfile
$ sudo mkswap /swapfile
$ sudo swapon /swapfile
$ sudo vim /etc/fstab
Insert: /swapfile swap swap defaults 0 0
$ sudo swapon --show
(make sure swap is active)

Now, build the workspace:

This will take a long time to build on NavQ. In our experience, it takes anywhere from 45 minutes to an hour. Make sure you have a stable connection to NavQ over UART or SSH, and do not let the NavQ lose power!

~$ ./px4_ros_com_ros2/src/px4_ros_com/scripts/build_ros2_workspace.bash

Sourcing ROS2 bash files

In order to run all of your specific ROS2 software successfully, you must source the install/setup.bash files in each of your ROS2 workspace folders. Add the following lines to your .bashrc to do so:

source /opt/ros/foxy/setup.bash
source ~/px4_ros_com_ros2/install/setup.bash

Next steps

Continue to the next page to set up a systemd service that will automatically start the micrortps agent on your NavQ. The guide will also cover how to automatically start the client on the FMU.