global_plan_navigate_bridge

Adapter between a topic-publishing global planner and AirStack's task-executor local planner. The DROAN local planner (droan_gl, from the asm_droan module used by the full_droan* stacks) plans only while a NavigateTask action goal is active, and it rejects a second goal while one is running. The default MIGHTY local planner (full_default) instead follows the global_plan topic itself and needs no adapter. The random-walk planner drives it as an action client itself; planners that simply publish a nav_msgs/Path on global_plan — the exploration_planner and raven modules, or any external planner following the interface conventions — need this bridge to make the vehicle move.

Architecture

flowchart LR
    GP[global planner<br/>exploration_planner / raven / ...] -->|"global_plan (nav_msgs/Path)"| B[global_plan_navigate_bridge]
    B -->|"NavigateTask goal<br/>(cancel active, then send)"| LP[droan_gl<br/>tasks/navigate]
    LP -->|trajectory_segment_to_add| TC[trajectory_controller]

Behaviour:

1. A new plan whose pose count or final pose changed (by more than replan_min_change_m) cancels the active goal and, once the cancel is acknowledged, sends the new plan as a NavigateTask goal. droan_gl may still report "task already active" for a moment after the cancel, so the send is retried (send_retry_period_s, max_send_retries).
2. Identical re-publications (planners typically re-send their current plan periodically) are ignored.
3. An empty Path cancels the active goal (cancel_on_empty_plan).
4. ~/set_enabled (std_srvs/SetBool) pauses/resumes the bridge; disabling cancels the active goal.

Interfaces

Declared in launch/global_plan_navigate_bridge.launch.xml (canonical defaults; rewire from the stack entry file only):

Launch arg	Default	Direction	Type
global_plan_navigate_bridge_global_plan_topic	/$ROBOT_NAME/global_plan	in	nav_msgs/Path
global_plan_navigate_bridge_navigate_task_action	/$ROBOT_NAME/tasks/navigate	client	task_msgs/action/NavigateTask
global_plan_navigate_bridge_config	config/global_plan_navigate_bridge.yaml	—	parameter file

Service: /$ROBOT_NAME/global_plan_navigate_bridge/set_enabled (std_srvs/SetBool).

Parameters

Parameter	Default	Description
goal_tolerance_m	1.0	Passed through in every NavigateTask goal
replan_min_change_m	0.5	Final-pose displacement below which a re-published plan is treated as unchanged
cancel_on_empty_plan	true	An empty Path cancels the active goal
send_retry_period_s	0.5	Retry period after a rejected send
max_send_retries	10	Give up (drop the plan) after this many rejections
enabled	true	Initial state of the set_enabled switch

Usage

Include it in a DROAN-based stack whose global planner publishes plans on a topic, right after that planner's include (the MIGHTY-based full_exploration and full_raven stacks do not need it):

<include file="$(find-pkg-share global_plan_navigate_bridge)/launch/global_plan_navigate_bridge.launch.xml" />

full_default does not include it: its random-walk planner is its own NavigateTask client and MIGHTY follows global_plan directly.

Testing

Hermetic unit tests for the plan-change rule live in test/ and run with airstack test -m unit (listed in tests/colcon_unit_test_packages.yaml) or colcon test --packages-select global_plan_navigate_bridge in the robot container.