PX4 Developer Summit | Virtual 2020

micro-ROS is a Robot Operating System specifically tailored for embedded and resource-constrained platforms, such as microcontrollers.

It is an open-source software that runs on Real Time Operating Systems (RTOS), such as NuttX and Zephyr. Above that, it runs the ROS 2 stack with a few microcontrollers-specific improvements. It offers powerful developer tools, such as a complete build system for different RTOSes and hardware platforms, and the whole pool of robotic applications available in a ROS 2 environment.

micro-ROS promotes microcontrollers to the ROS 2 world, and uses as a middleware eProsima Micro XRCE-DDS, that is, DDS for eXtremely Resource-Constrained Environments, a software solution allowing the integration of microcontrollers into the DDS world.

DDS is a communication protocol that deploys a Data-Centric Publisher-Subscriber model, whose implementation eProsima Fast DDS is the default middleware supported by ROS 2. The protocol used by eProsima Fast DDS to exchange messages over standard networks is the Real-Time Publish-Subscribe protocol (RTPS), an interoperability wire protocol for DDS.

Following the latest successful results of the integration of micro-ROS into microcontrollers and devices running different RTOSes, including NuttX, we suggest that micro-ROS could be seamlessly and profitably integrated into the PX4 ecosystem in the near future.

While the task of integrating PX4 into the DDS world has been dealt with by means of the micro-RTPS bridge so far, the present proposal hinges on the need for a more mature, flexible and secure interface with DDS that would be carried out by micro-ROS, and can be seen as a natural extension of the work done in the past over the micro-RTPS bridge. Actually, micro-RTPS was the first prototype and the origin of the micro-ROS project.

We therefore deem reasonable and desirable the exploration of XRCE-DDS and the possible migration from the micro-RTPS bridge implementation to micro-ROS in the PX4 ecosystem.

This talk will focus on presenting all of the concepts mentioned above, namely DDS, RTPS, XRCE-DDS and micro-ROS. We will then go over how both micro-ROS and the micro-RTPS bridge work, presenting a comparison between them. Finally, we will trace an ideal roadmap to migrate from the micro-RTPS bridge to micro-ROS, furthermore adding support of the latter to a platform like the Auterion Skynode.