feat(fleet): multi-robot SLAM — map sharing + cooperative exploration (Issue #134)
New packages:
saltybot_fleet_msgs — 4 msgs (RobotInfo, MapChunk, Frontier, FrontierArray)
+ 2 srvs (RegisterRobot, RequestFrontier)
saltybot_fleet — 4 nodes + 2 launch files + config + CLI tool
Nodes:
map_broadcaster_node — zlib-compress local OccupancyGrid → /fleet/maps @ 1Hz
+ /fleet/robots heartbeat with battery/status
fleet_manager_node — robot registry, MapMerger (multi-grid SE2-aligned merge),
frontier aggregation, /fleet/request_frontier service,
heartbeat timeout + stale frontier re-assignment
frontier_detector_node — scipy label-based frontier detection on merged map
→ /fleet/exploration_frontiers_raw
fleet_explorer_node — Nav2 NavigateToPose cooperative exploration state machine:
IDLE→request→NAVIGATING→ARRIVED→IDLE + STALLED backoff
Supporting modules:
map_compressor.py — binary serialise + zlib OccupancyGrid encode/decode
map_merger.py — SE(2)-transform-aware multi-grid merge with conservative
obstacle inflation (occupied beats free on conflict)
frontier_detector.py — numpy frontier mask + scipy connected-components + scoring
landmark_aligner.py — ArUco-landmark SE(2) estimation (Horn 2D least-squares)
to align robot map frames into common fleet_map frame
Topic layout:
/fleet/maps MapChunk per-robot compressed grids
/fleet/robots RobotInfo heartbeats + status
/fleet/merged_map OccupancyGrid coordinator merged output
/fleet/exploration_frontiers FrontierArray consolidated frontiers
/fleet/status String (JSON) coordinator health
/<robot_ns>/rtabmap/map input per robot
/<robot_ns>/rtabmap/odom input per robot
/<robot_ns>/navigate_to_pose Nav2 action per robot
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
sl-perception
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