ROS2 Powered PX4 - PX4 Developer Summit 2019
Channel: PX4 Autopilot - Open Source Flight Control.
Date: 03/07/2019

Nuno Marques
Software Engineer, Drone Tech Consultant

As we look towards more complex systems, PX4-powered UAS will become a subsystem in a larger system. With the current developments of ROS 2 and its infrastructure, the demand to make PX4 capable of integrating with such framework has increased, besides the current already supported ROS-Mavlink bridge package, MAVROS.

The ability to isolate telemetry links over Mavlink and provide a more tight integration of the PX4 internal communication architecture with the companion systems lead us to explore the benefits of DDS (Data Distribution Service) standard and, for that reason, implement a bridge that allows PX4 uORB publisher/subscriber architecture to connect to RTPS (Real Time Publish-Subscribe) protocol participants over the same DDS standard layer, while looking to gradually abandon the usage of Mavlink in companion computer links.

As being the default middleware of ROS2, eProsima Fast-RTPS was the chosen RTPS implementation to bridge PX4 uORB topics with ROS 2 nodes.

This presentation will show how the px4_ros_com, a ROS2 package for bridging PX4 and ROS2 through a micro-RTPS bridge - a slimmed down RTPS point-to-point link using micro-RTPS (client/FCU side) and Fast-CDR (agent/companion side) for serialization and deserialization - is architecture and implemented, how can it be used and provide an overall status about its current development state and future works. It will also be offered a pros/cons comparison between using RTPS-supported and Mavlink-supported communication in PX4 and companion computer links.