This package contains a ROS 2 Humble wrapper for OpenSlam's Gmapping, based on http://wiki.ros.org/gmapping. The gmapping package provides laser-based SLAM (Simultaneous Localization and Mapping), as a ROS node called slam_gmapping. Using slam_gmapping, you can create a 2-D occupancy grid map (like a building floorplan) from laser and pose data collected by a mobile robot.

Special thanks to Project MANAS for their contribution in migrating the SLAM method to ROS 2 Eloquent: https://github.com/Project-MANAS/slam_gmapping

ros2 launch slam_gmapping slam_gmapping_launch.xml

The node slam_gmapping node takes in sensor_msgs/LaserScan messages and builds a map (nav_msgs/OccupancyGrid). The map can be retrieved via a ROS topic or service.

• tf (tf/tfMessage):
  Transforms necessary to relate frames for laser, base, and odometry.

• scan (sensor_msgs/LaserScan):
  Laser scans to create the map from.

• map_metadata (nav_msgs/MapMetaData):
  Provides map metadata, which is latched and updated periodically.

• map (nav_msgs/OccupancyGrid):
  Provides the map data, which is latched and updated periodically.

• ~entropy (std_msgs/Float64):
  Estimates the entropy of the map.

• dynamic_map (nav_msgs/GetMap):
  Call this service to get the map data.

• ~throttle_scans (int, default: 1):
  Process 1 out of every this many scans (set a higher number to skip more scans).

• ~base_frame (string, default: "base_link"):
  The frame attached to the mobile base.

• ~map_frame (string, default: "map"):
  The frame attached to the map.

• ~odom_frame (string, default: "odom"):
  The frame attached to the odometry system.

• ~scan_topic (string, default: "/scan"):
  The laser scan topic.

• ~map_update_interval (float, default: 5.0):
  Interval in seconds between map updates. Lowering this number updates the occupancy grid more frequently, at the expense of computational load.

• ~maxUrange (float, default: 80.0):
  Maximum usable range of the laser; beams are cropped to this value.

• ~sigma (float, default: 0.05):
  Sigma used by the greedy endpoint matching.

• ~kernelSize (int, default: 1):
  Kernel size used for searching correspondence.

• ~lstep (float, default: 0.05):
  Optimization step in translation.

• ~astep (float, default: 0.05):
  Optimization step in rotation.

• ~iterations (int, default: 5):
  Number of iterations of the scan matcher.

• ~lsigma (float, default: 0.075):
  Sigma of a beam used for likelihood computation.

• ~ogain (float, default: 3.0):
  Gain used for likelihood evaluation to smooth resampling effects.

• ~lskip (int, default: 0):
  Number of beams to skip in each scan. Only every (n+1)th laser ray is used for matching (0 = take all rays).

• ~minimumScore (float, default: 0.0):
  Minimum score for considering the scan match outcome as good. Useful to prevent pose jumps in open spaces when using scanners with limited range (e.g., 5m).

• ~srr (float, default: 0.1):
  Odometry error in translation as a function of translation (rho/rho).

• ~srt (float, default: 0.2):
  Odometry error in translation as a function of rotation (rho/theta).

• ~str (float, default: 0.1):
  Odometry error in rotation as a function of translation (theta/rho).

• ~stt (float, default: 0.2):
  Odometry error in rotation as a function of rotation (theta/theta).

• ~linearUpdate (float, default: 1.0):
  Process a scan each time the robot translates this distance.

• ~angularUpdate (float, default: 0.5):
  Process a scan each time the robot rotates this angle.

• ~temporalUpdate (float, default: -1.0):
  Process a scan if the last processed scan is older than the specified update time (in seconds). A value less than zero disables time-based updates.

• ~resampleThreshold (float, default: 0.5):
  Neff-based threshold for resampling.

• ~particles (int, default: 30):
  Number of particles in the filter.

• ~xmin (float, default: -100.0):
  Initial map size in meters (minimum x-coordinate).

• ~ymin (float, default: -100.0):
  Initial map size in meters (minimum y-coordinate).

• ~xmax (float, default: 100.0):
  Initial map size in meters (maximum x-coordinate).

• ~ymax (float, default: 100.0):
  Initial map size in meters (maximum y-coordinate).

• ~delta (float, default: 0.05):
  Map resolution in meters per occupancy grid cell.

• ~llsamplerange (float, default: 0.01):
  Translational sampling range for likelihood computation.

• ~llsamplestep (float, default: 0.01):
  Translational sampling step for likelihood computation.

• ~lasamplerange (float, default: 0.005):
  Angular sampling range for likelihood computation.

• ~lasamplestep (float, default: 0.005):
  Angular sampling step for likelihood computation.

• ~transform_publish_period (float, default: 0.05):
  Interval (in seconds) between transform publications. Set to 0 to disable broadcasting transforms.

• ~occ_thresh (float, default: 0.25):
  Threshold on occupancy values in gmapping. Cells with greater occupancy are marked as occupied (100 in sensor_msgs/LaserScan).

• ~maxRange (float):
  Maximum range of the sensor. To represent regions with no obstacles within range as free space, set maxUrange < maximum range of real sensor <= maxRange.