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Description

The sections below describe the API of the package. The interface is similar to gmapping (http://wiki.ros.org/gmapping) but the package supports different particle filter algorithms, range-only SLAM and can work with several grid maps simultaneously.

This package supports the following Particle Filter SLAM algorithms (more details at http://www.mrpt.org/tutorials/slam-algorithms/rbpf-slam_algorithms/):

• Sequential Importance Resampling – SIR with the “standard” proposal distribution (enum value: pfStandardProposal)
• Auxiliary Particle Filter – APF with the “standard” proposal distribution (enum value: pfAuxiliaryPFStandard)
• Optimal proposal distribution (enum value: pfOptimalProposal)
• Approximate Optimal Sampling – A rejection sampling-based approximation to the optimal proposal when a closed-form expression is not available (enum value: pfAuxiliaryPFOptimal)

These algorithms allow building grid map or range-only map.

Further documentation

The ROS node mrpt_rbpf_slam is a wrapper for the C++ class mrpt::slam::CMetricMapBuilderRBPF, part of MRPT. Check out the documentation of this class for further details.

This node has been designed to provide an interface similar to that of slam_gmapping for the convenience of users who already know this package.

The coordinate frames are implemented according to the convention ROS REP 105: "Coordinate Frames for Mobile Platforms".

Usage

In order to use mrpt_rbpf_slam package it is necessary to install the latest MRPT build and the mrpt_navigation (see also the tutorial). Additionally, it is possible to install mvsim simulator which allows to make simulations with RBPF SLAM.

Example

The following video demonstrates the work of the gridmap RBPF-based SLAM using Rviz and MRPT GUI:

To run the example of the gridmap RBPF SLAM in online mode, use the following command:

roslaunch mrpt_rbpf_slam rbpf_slam.launch

To run the example of the gridmap RBPF SLAM from *.rawlog file, use the following command:

roslaunch mrpt_rbpf_slam rbpf_slam_rawlog.launch

another example is available by running

roslaunch mrpt_rbpf_slam rbpf_slam_rawlog.launch example:=2

Another possibility is to use the RBPF SLAM package for the range-only SLAM. The following video demonstrates work of the range only RBPF-based SLAM using Rviz and MRPT GUI:

The example usage of the range only RBPF SLAM in online mode:

roslaunch mrpt_rbpf_slam ro_slam.launch

The example usage of the range only RBPF SLAM from .rawlog file:

roslaunch mrpt_rbpf_slam ro_slam_rawlog.launch

The following video shows use of the mrpt_rbpf_slam package with mvsim simulator:

The example usage of the mrpt_rbpf_slam with mvsim simulator:

roslaunch mrpt_rbpf_slam mvsim_slam.launch

The package was developed and tested as part of the Google Summer of Code 2016 project. The following video shows the final tests carried out with the robot:

Nodes

mrpt_rbpf_slam

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

Subscribed Topics

tf (tf/tfMessage)

• Transforms necessary to relate frames for laser, base, and odometry (see below)

scan (sensor_msgs/LaserScan)

• Laser scans to create the map from

beacon (mrpt_msgs/ObservationRangeBeacon)

• The beacons for range only map

Published Topics

particlecloud_beacons (geometry_msgs/PoseArray)

• The particle cloud where each particle represents the possible location of the beacon

map (nav_msgs/OccupancyGrid)

• Occupancy grid map topic

particlecloud (geometry_msgs/PoseArray)

• Estimate of the robot's pose

beacon_viz (visualization_msgs/MarkerArray)

• Visualization of the beacons with ID

Parameters

~global_frame_id (string, default: "map")

• The frame attached to the map

~base_frame_id (string, default: "base_link")

• The frame attached to the mobile base

~odom_frame_id (string, default: "odom")

• The frame attached to the odometry system

~sensor_source (string, default: "scan")

• The name of topics with 2d laser scans or beacons (the name of topic should contain word "scan" or "beacon")

~ini_filename (string, default: None)

• The path to the ini file with MRPT settings for SLAM (see tutorial folder)

~rawlog_filename (string, default: None)

• The path to rawlog file (if the rawlog file does not exist, the SLAM starts in the online mode)

~rawlog_play_delay (float, default: 0.1)

• Delay for replaying SLAM from the rawlog file

Required tf Transforms

<the frame attached to incoming scans> → base_link

• The relative pose of the laser sensor w.r.t. the robot. Usually a fixed value, broadcast periodically by a robot_state_publisher, or a tf static_transform_publisher.

base_link → odom

• The robot odometry, provided by the odometry system (e.g., the driver for the mobile base)

Provided tf Transforms

map → odom

• The current estimate of the robot's pose within the map frame

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