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Usage of Groot with ROS2

I started to experiment with navigation2 and especialy the BT part for more complex behaviors and recoveries. It somehow expected to also find a debug and visualization tool, but so far I couldn’t find one. Groot does not work directly, so I wanted to know if there are plans to make it usable or how other developers use BTs in ROS2

There is an open PR working on this:


my ability to support Groot is limited and usually I prioritize my open source projects based on the feeling of their usefulness to the community. I was not sure about how many people where actually using Groot.

I was not aware of the open issue in navigation2… interesting to know.

I haven’t maintained much this part. If you find any actual bug, let me know.

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Hey there… :smiley:
Cool to see my PR spotted.

I’m currently stuck on 2 things:

That the Groot PR (mentioned by me in this PR above) including my PR of this Groot PR gets accepted by @facontidavide . That way reloading of the BT does not crash Groot… :slight_smile: I just extended the PR for this a little bit, this way I was not able to manually crash it with random connects / disconnects / reset of Nav2 lifecycle nodes etc.

The second thing is CI:
I went a little bit too far down the rabbit hole and got confused why there is ros2/launch and ros2/ros_launch …
What I want to implement is testing with the optional parameter “enable_groot_monitoring” while not creating a new complete param file of the nav2 parameters…
So basically substituting this one paramerter with the value “True” while keeping the rest of the params.yaml untouched. = With existing ROS2 tools. #helpwanted !! @mikeferguson ? :heart:
(Alternatively fixing the original nav2-thing for this: )

Also, documentation for how to use Groot with nav2 is happening this weekend. (not hard at all :smiley: )

So the PR is sort of ready, just need to add the nice last bits.

Also @NikolasE are you already in the navigation2 slack? :slight_smile: Would be cool to know what you are up to with BTs!

Merged. Better late than never.

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Thanks! There are just some small fixes missing. I put them all together in

@facontidavide Would be cool if you could merge this as well. I took the earlier file conflicts of #61 into account and retested it with nav2:main .

On the launch_file param substitution:

I found the root cause.The works fine, but only for 1-dimensional dicts and not
params = {'bt_navigator':{'ros__parameters':{'enable_groot_monitoring' : 'True'}}}

If I use this, the value for ‘bt_navigator’ gets completely replaced with just ‘ros__parameters’ as a value and not the rest of the multi-dimensional dict. I’m currently thinkering on this issue… maybe somebody else has a hint or something completely else that gets the job done? :slight_smile:
Maybe @wjwwood, do you know something/someone that could help here?
(tl;dr Rest of the issue is mentioned in my previous post, the CI section)


CI / YAML Parameter Substitution user-“bug”: I found it :white_check_mark:

I was to focused on getting the multi-dimensional key as an Input of RewrittenYaml()… But, RewrittenYaml has a recursive iterator built-in that searches for the key on any level of the yaml-params dict… :upside_down_face: But this happens only when the sub-function perform(context) with a given LaunchContext is triggered, which did not happen in the existing CI tests I skimmed through…
@smac probably also interesting for you :slight_smile: - will be included in the PR and probably worth some docu as well.

Looks like this PR is getting finished soon… :partying_face:

Hey @facontidavide,

just a friendly ping! :slight_smile:
As my PR of nav2 and its documentation are slowly reaching a finish line, it would be cool if you have a moment to merge my PR for Groot!

Thank you!