Feature Request | Dynamic planner selection in runtime

[nakai-omer]

Feature request

Feature description

Currently the planner server supports configuring multiple planners, nevertheless the default bt tree only supports a single planner, which is also hard-coded with id: GridBased. So, if you want to enjoy the awesome bt_navigator server with NavigateToPose, or NavigateThroughPoses, actions and select the planner you want in runtime, you can't. There have been previous discussions on how to enable multiple planners (open-navigation/docs.nav2.org#147, #3000), but they require changing the behavior tree, writing new bt nodes, or creating multiple action servers, etc.
Here I would like to propose a backward compatible, minimum changes required, that will easily add the option to control which planner is used in runtime, either from the simple commander api, or via the NavigateToPose or NavigateThroughPoses actions.

Example use case for this:
Running a coverage path planner, and once the path is over running a planner to plan the way back to the docking station.

Implementation considerations

Implemented in #3565 and #3566

This will also be a step towards a super easy fix for: #3269

[SteveMacenski]

Empty ticket... closing

[nakai-omer]

@SteveMacenski A glitch while writing the feature request, I have updated it with the details, may you please reopen?

[SteveMacenski]

See the planner selector (or other selector) BT nodes. You can change them at runtime however you like. That "hardcode" is just the default BT. You can make that a BT blackboard variable like {path} which can pass the planner any ID you like. Its then on you to decide for your application how to populate / change that variable. The selector BT nodes are one way, but there are many options if there's a more natural API for your application. If there's another general way that would be interesting to have, I'd be happy to chat about a new set of selector nodes via a different communication or decision logic method!