feat: ArUco marker detection for docking (Issue #627)
New package saltybot_aruco_detect — DICT_4X4_50 ArUco detection from
RealSense D435i RGB, pose estimation, PoseArray + dock target output.
aruco_math.py (pure Python, no ROS2): rot_mat_to_quat (Shepperd),
rvec_to_quat (Rodrigues + cv2 fallback), tvec_distance, tvec_yaw_rad,
MarkerPose dataclass with lazy-cached distance_m/yaw_rad/lateral_m/quat.
aruco_detect_node.py (ROS2 node 'aruco_detect'):
Subscribes: /camera/color/image_raw (30Hz BGR8) + /camera/color/camera_info.
Converts to greyscale, cv2.aruco.ArucoDetector.detectMarkers().
estimatePoseSingleMarkers (legacy API) with solvePnP(IPPE_SQUARE) fallback.
Dock target: closest marker in dock_marker_ids (default=[42], empty=any),
filtered to max_dock_range_m (3.0m).
Publishes: /saltybot/aruco/markers (PoseArray — all detected, camera frame),
/saltybot/aruco/dock_target (PoseStamped — closest dock candidate,
position.z=forward, position.x=lateral), /saltybot/aruco/viz (MarkerArray
— SPHERE + TEXT per marker, dock in red), /saltybot/aruco/status (JSON
10Hz — detected_count, dock_distance_m, dock_yaw_deg, dock_lateral_m).
Optional debug image with drawDetectedMarkers + drawFrameAxes.
corner_refinement=CORNER_REFINE_SUBPIX.
config/aruco_detect_params.yaml, launch/aruco_detect.launch.py.
test/test_aruco_math.py: 22 unit tests (rotation/quat math, distance,
yaw sign/magnitude, MarkerPose accessors + caching).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
sl-perception
1fd935b87e