ROS 2 and Real-time

Next Generation ROS
18

@vmayoral @iluetkeb @davecrawley et al thank you very much for your feedback and also apologies for not replying earlier.

I am with you and I agree that we need a use case. Not listing an item to decide on the use case was an oversight on my side. However I got the following use cases from your replies:

  1. consumer robots (Ingo)
  2. warehouse logistics robots (David)
  3. mobile manipulation robots (Victor)
  4. autonomous driving robots/cars (Dejan, Geoff)

If you want to plus one any of above items or add another use case please let me know.

Otherwise it is clear that alone above 4 use cases are vastly different and will have different requirements, different HW, different middleware and probably also different control and data flows (which will result in different node architectures).

Said that I guess we have 2 options to start from here:

  1. select one of the use cases above and probably loose interest from people having other uses case.
  2. focus on somewhat generic parts of ROS 2 that will help independently of the selected use case.
    My reading of your comments is that these parts are the following ones:
    1. create rmw layers for static and real-time middleware (RTI Connext Micro, Micro-XRCE-DDS)
    2. perform memory audit in rmw, rcl and rclcpp (remove unneeded memory allocations)
    3. split memory allocation in init and runtime phases, avoid memory fragmentation
    4. remove all blocking calls (or replace with timed calls, e.g. mutex vs timed_mutex )
    5. implement real-time pub/sub (either using Waitset or modified Callback/Executor)
    6. integrate tools for static and dynamic code analysis (PCLint, LDRA, Silexica, LTT-ng)
    7. Create node architecture for deterministic execution (policy for message aggregation, nodes cohesion, parallelization, local error handling …)
    8. Create a design for global error handling (history of failures, core dumps, fail-safe mechanism, …)
      1. Create CI for RT testing (e.g. https://github.com/ros2/ros2/issues/607#issuecomment-460319513 )

I am leaning towards the second option.

I’d like to invite for a meeting next week to decide on above and to kick off the work. Could you guys meet on

Note that we have an interest across the globe, so getting a meeting friendly time in every zone will be impossible.

1 Like