PX4 Messages in ROS 2
Interact with uORB messages in APX4 using ROS 2
This is a preview feature which might change with AuterionOS 3.0
uORB messages published by the FMU can be made available to AuterionOS apps by enabling the Micro XRCE-DDS (uXRCE-DDS) bridge for use in ROS 2 applications. The bridge supports communication in both directions, meaning ROS 2 applications can receive certain uORB topics from APX4, as well as send messages to the flight controller.
Configuration
Drone Manufacturers need to follow the instructions linked below to enable Micro XRCE-DDS in AuterionOS:
Micro XRCE-DDSPlease contact the vehicle manufacturer or success@auterion.com if you are developing an application for an Auterion-powered vehicle and require help with the setup of Micro XRCE-DDS.
ROS 2 topic naming
When Micro XRCE-DDS is enabled, a pre-determined set of uORB topics coming from APX4 will be published in ROS 2. The ROS 2 topics are prefixed with /fmu/out/. For example, a ROS 2 node can receive vehicle_odometry uORB messages by subscribing to /fmu/out/vehicle_odometry.
Similarly, Micro XRCE-DDS subscribes to a set of ROS 2 topics to be published as uORB topics in the FMU. These ROS 2 topics are prefixed with /fmu/in. For example, a ROS 2 node can publish to the vehicle_visual_odometry uORB topic by publishing to /fmu/in/vehicle_visual_odometry.
ROS 2 message definitions
The ROS 2 message headers are built from the (uORB) message definitions and are available by the px4_msgs ROS 2 package: https://github.com/PX4/px4_msgs.
To ensure compatibility, the ./msg directory of px4_msgs that is being used to compile the AuterionOS application should have the same contents as the ./msg directory of the APX4 firmware that is being used.
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