AMCL and map_server were ported to ROS2 with minimal functional changes, but some refactoring.
- amcl -> nav2_amcl
- map_server -> nav2_map_server
In addition, move_base itself has been split into multiple components:
- nav2_bt_navigator (replaces move_base)
- nav2_navfn_planner (replaces global_planner)
- nav2_dwb_controller (replaces local_planner)
The nav2_bt_navigator replaces move_base at the top level, with an Action interface to call the global planner and controller with a configurable tree-based action model.
The nav2_bt_navigator itself is also an Action Server and can also be replaced with other implementations. It uses Behavior Trees to make it possible to have more complex state machines and to add in recovery behaviors as additional Action Servers. See nav2_bt_navigator for that implementation. (currently WIP in Pull request 91)
The nav2_navfn_planner is ported from the navfn package in ROS, but adds the Task Server interface to enable it to be strongly decoupled from the nav2_bt_navigator.
Similarly, the nav2_dwb_controller is ported from the dwb controller package, and also adds a Task Server interface to also enable it to be decoupled from the nav2_bt_navigator.
All these changes make it possible to replace any of these nodes at launch/run time with any other algorithm that implements that same interface.
See each package README.md for more details