Update docs to better communicate dynamic footprint support

[SteveMacenski]

Footprints can be updated dynamically depending on arm pose, load being carried, etc. Document this explicitly and visibly so that folks are aware (and what topics to publish to).

CC @tonynajjar have any input here to share given you do this as I'm looking to better document it for the community?

[tonynajjar]

Do I understand correctly that this issue is to document custom solution built to enable dynamic footprints? If yes, why? How is this useful to the community?

(Or are you gathering requirements for the implementation of a Nav2 generic way)

[SteveMacenski]

The goal is to document that its even possible at all to do this and how to do it (e.g. what topics to publish to, perhaps some high level guidance about how to compute the updated footprints). It came up in the User Survey that several people asked for this feature that already exists that they were not aware of the fact that you can already use dynamic footprints. So I want to document it more explicitly and clearly that this is possible / easy to do

So from your experience, is it just publishing to the local/global costmap's footprint topics and you're done? Any other subtlety I should be aware of when writing this up from your experience?

[tonynajjar]

@jplapp @HovorunB friendly ping as you've worked on this more closely than I have, feel free to put some thoughts in.

[SteveMacenski]

https://github.com/ros-planning/navigation.ros.org/pull/484

If there's more detail that is worth remarking upon, please follow up here and I'll update it further!

[SteveMacenski]

@tonynajjar & Team: I opened a ticket to make a tutorial showing this feature https://github.com/ros-planning/navigation.ros.org/issues/485

Would you be open to contributing it? It can be very short and sweet, I just want to show this in action and I think given that you're doing this already, you could have some minimal example that you could put together very quickly that would help the rest of the community.

I'd just be looking for:

• A quick 2-5 sentence description that this is possible and the topics that should be updated
• A quick 1 sentence set of examples of why this is important (picked up a pallet, robot arm in a different state, etc)
• An example (probably python for simplicity) node which computes a new footprint. For all I care, its just gain scheduled (robot in X state -> use Y hardcoded value), though having something that computes something might be illustrative since as @tonynajjar and I discussed, a general node to do this probably isn't realistic, so this documentation is going to be as close as we get
• A 20 second video showing it running in rviz with the footprint updating

If you got that together, I'd personally take the responsibility of editing it to get it ready for publication so you can move on. Is that something you'd be open to contributing? I'd greatly appreciate it and help pay it forward for this great capability!

[david-wb]

Hello, I am trying to do exactly this, and a tutorial would have been helpful. Is it as simple as publishing a polygon to a single topic? If you could let me know the ROS message type for publishing a polygon and the topic name to use, I would be happy to help write a brief tutorial/demo on dynamically updating a robot's footprint.