ROS 2 and Real-time

[vmayoral]

Happy to see this kicking off and willing to collaborate as pointed out previously.

@Dejan_Pangercic

To this date we have the following articles about real-time in ROS 2:

I’d add the following articles to the list above which comes from a previous discussion:

• Time Synchronization in modular collaborative robots
• Towards a distributed and real-time framework for robots: Evaluation of ROS 2.0 communications for real-time robotic applications
• Real-time Linux communications: an evaluation of the Linux communication stack for real-time robotic applications
• Time-Sensitive Networking for robotics

and this session in the last ROS-I conference in Europe: System Integration and Modularity in Robotics using ROS

@Dejan_Pangercic

Since real-time is not something that can start and stop within the ROS 2 “borders”, we would like to propose to analyse an entire stack, from the hardware platform to the applications written with ROS 2.

This is the right approach. Same applies to safety and security.

@Dejan_Pangercic

Pick real-time capable hardware platform. Decide if we go multi-core many-core or uP.

This is a very troublesome topic. One of the points we should answer before selecting any hardware platform is answering the question of “what’s the actual (real-time) target of this WG?” Is it going to be soft real-time? hard-real time? What are the use cases we have in mind for real-time? (this should probably come from the groups driving the work).

Things are very different depending on where we want to go.

We’ve worked on this topic for several years already and humbly accumulated a few good (and not so good) experiences. We ended up moving into a hard-real time capable hardware platform in close collaboration with Xilinx (Intel has similar, rather good alternatives) however I wouldn’t claim such platform will be valid for (hard) real-time in any scenario. Obtaining (hard) real-time typically requires a good definition of the target (whether it’s a joint driver, a LIDAR driver or a motion planner within MoveIt).

There’s no silver bullet and maintaining a specific hardware platform for hard (or even soft) real-time requires a huge amount of resources.

@Dejan_Pangercic

Create CI for RT testing (e.g. https://github.com/ros2/ros2/issues/607#issuecomment-460319513 )

That’s us. I’ll be giving an update today but should be ready in a couple of months. Again, very open to include additional hardware platforms, reach out for more information on how to do so.

@Dejan_Pangercic

We are requesting for comments:

1. Do you have items to be added/removed from above list?
2. Do you want to join this working group? We will form a regular ROS working group that uses Discourse for discussions and holds video and in-person meetings.

We are aiming for our first video meeting next week.

We’re obviously in. Do you need help organizing the meetings? Happy to support and plan the events or organize the meeting notes.