add nav2_gps_waypoint_follower_demo

[jediofgever]

Related original ticket; https://github.com/ros-planning/navigation2/issues/1631 Add example package nav2_gps_waypoint_follower_demo that demonstrates usage of nav2_gps_waypoint_follower introduced here.

[jediofgever]

I think with Python the explicity might have been decreased. But I believe with current explicit form this tutorial will be straightforward to follow and will be convertible to Python if someone needs that.

I debate to myself if this is worth it

It is very well worth it, but I believe if we do that we will be aiming for application code rather than demo code. We have showcased core tools in order to use gps waypoint following. It is then up to user whether they just want to try out this or taking it next step as aiming an application following the sample code given here.

[SteveMacenski]

It is very well worth it, but I believe if we do that we will be aiming for application code rather than demo code. We have showcased core tools in order to use gps waypoint following. It is then up to user whether they just want to try out this or taking it next step as aiming an application following the sample code given here.

Fair enough. Do you think there's an application code to be built from this at a later time? I don't have a clear vision of what that would look like to be sufficiently general that wouldn't largely just turn into another action server relaying points to the WP action server.

[jediofgever]

What I meant by application was, for instance you can develop a gui application which in back uses this client to relay points to FollowGPSPoints, with stop/pause/cancel buttons. Actually RVIZ already does this, but you may not want to ship RVIZ as your software product :). Clearpath actually has a product which exactly falls into focus of this demo, the only thing this demo lacks from their product is a gui application that helps to extract GPS waypoints and utility functions to start, stop navigation.

[SteveMacenski]

Got it, but you don't see this project becoming something like that. That's kind of what I was fishing for. If we thought we could make this "follower operations" server could/should be generalized to that level, perhaps its worth considering this for the main stack.

But this is good for now with the docs to match. We can always elevate this into Nav2 itself if we like in the future.

[jediofgever]

you don't see this project becoming something like that.

It can be elevated to something like that with some effort. But how to extract GPS waypoints is the question here, if it was to be added to main stack.

[SteveMacenski]

I suppose we don't really have an analog for that for just normal waypoints, other than the rviz plugin which would work with with GPS (since the rviz displays are natively using the navsat transform to assign map goals). We can leave it as demo code.

What you have here now seems good. There's a couple of models but that's much more reasonable to keep. We'll revisit this once the main PR is ready to be merged but this looks good to me.

[SteveMacenski]

Superseded!