Technical Documentation: Mapping Screen

Architecture

This screen manages the state of the robot's SLAM engine. It relies heavily on the OccupancyGrid data type and Lidar scan feedback.

Technical Details

• File Path: lib/screens/mapping_screen.dart
• ROS Integration:
  • Subscriber: /map (Type: nav_msgs/OccupancyGrid) - Receives the live SLAM map.
  • Subscriber: /scan (Type: sensor_msgs/LaserScan) - Receives Lidar data for visualization.
  • Services: /save_map, /start_mapping, /stop_mapping.
• Database Integration: Uses ros.storeCurrentMapToDb to trigger the backend conversion of the ROS OccupancyGrid into the permanent .yaml and .pgm formats.

Map Rendering

• Grid Processing: The MapView widget converts the OccupancyGrid (values 0 to 100) into grayscale pixels:
  • 0: White (Free Space)
  • 100: Black (Obstacle)
  • -1: Grey (Unknown)
• Coordinate Sync: Ensures map coordinates are aligned with the Odom frame so the robot's path is drawn correctly over the scanned area.

SLAM Control

• Lifecycle Management: Commands are sent via ROS Services to the backend bridge, which manages the launch/shutdown of SLAM nodes on the robot's Linux OS (Ubuntu/ROS 2).