@@ -66,7 +66,7 @@ The nav2_behavior_tree package provides several navigation-specific nodes that a
| BT Node | Type | Description |
|----------|:-------------|------|
| Backup | Action | Invokes the BackUp ROS2 action server, which causes the robot to back up to a specific pose. This is used in nav2 Behavior Trees as a recovery behavior. The nav2_recoveries module implements the BackUp action server. |
| ComputePathToPose | Action | Invokes the ComputePathToPose ROS2 action server, which is implemented by the nav2_navfn_planner module. |
| ComputePathToPose | Action | Invokes the ComputePathToPose ROS2 action server, which is implemented by the nav2_planner module. |
| FollowPath | Action |Invokes the FollowPath ROS2 action server, which is implemented by the nav2_dwb_controller module. |
| GoalReached | Condition | Checks the distance to the goal, if the distance to goal is less than the pre-defined threshold, the tree returns SUCCESS, otherwise it returns FAILURE. |
| IsStuck | Condition | Determines if the robot is not progressing towards the goal. If the robot is stuck and not progressing, the condition returns SUCCESS, otherwise it returns FAILURE. |
The NavfnPlanner is a [planning module](../doc/requirements/requirements.md) that implements the `nav2_behavior_tree::ComputePathToPose` interface.
The NavfnPlanner is a plugin for the Nav2 Planner server.
A planning module implementing the `nav2_behavior_tree::ComputePathToPose` interface is responsible for generating a feasible path given start and end robot poses. It provides the equivalent functionality to a [GlobalPlanner](http://wiki.ros.org/nav_core#BaseGlobalPlanner) in ROS1 [MoveBase](http://wiki.ros.org/move_base).
It provides the equivalent functionality to a [GlobalPlanner](http://wiki.ros.org/nav_core#BaseGlobalPlanner) in ROS1 [MoveBase](http://wiki.ros.org/move_base).
## Status
Currently, NavfnPlanner's core algorithm is a direct port from the ROS1 MoveBase [Navfn](http://wiki.ros.org/navfn) planner. The Navfn planning algorithm is based on the [Global Dynamic Window Approach](https://cs.stanford.edu/group/manips/publications/pdfs/Brock_1999_ICRA.pdf).
...
...
@@ -14,14 +14,6 @@ In A* mode (`use_astar = true`) A*'s search algorithm is not guaranteed to find
The Navfn planner assumes a circular robot and operates on a costmap.
## Task Interface
The [Navigation System]((../doc/requirements/requirements.md)) is composed of three tasks: NavigateToPose, ComputePathToPose and FollowPathToPose.
The DijkstraPlanner implements the Task Server interface for ComputePathToPose, specifically derives from `nav2_behavior_tree::ComputePathToPoseTaskServer`. The client to DijkstraPlanner is 'NavigateToPoseTask', which periodically sends requests to the path planner.
- Refactor Navfn. Currently difficult to modify/extend. [Issue #244](http://github.com/ros-planning/navigation2/issues/224)
- Implement additional planners based on optimal control, potential field or other graph search algorithms that require transformation of the world model to other representations (topological, tree map, etc.) to confirm sufficient generalization. [Issue #225](http://github.com/ros-planning/navigation2/issues/225)
