RoboND: Simultaneous Localization and Mapping (SLAM) using ROS and RTAB-Map

This project involves the creation of a 2D occupancy grid and a 3D octomap from a simulated environment using ROS and RTAB-Map. It is a POC to explore how to do Simulataneous Localization and Mapping (SLAM) in ROS.

RTAB-Map (Real-Time Appearance-Based Mapping) is a popular solution for SLAM to develop robots that can map environments in 3D. RTAB-Map has good speed and memory management, and it provides custom developed tools for information analysis.

This project uses the rtabmap_ros package, which is a ROS wrapper (API) for interacting with RTAB-Map. Here, a custom ROS package is created to interface with the rtabmap_ros package.

When the robot is launched we can teleop around the room to generate a proper map of the environment.

Link to Youtube video: https://www.youtube.com/watch?v=KCiHrqqdnSg

This project was done as part of the Robotics Software Engineer Nanodegree.

Description of the robot

The robot is a simulated differential drive robot created via URDF having the following sensors:

• A 2D Laser, providing sensor_msgs/LaserScan messages
• Odometry sensors, providing nav_msgs/Odometry messages
• 3D Camera - generates RGB-D images

ROS Packages used

• rtabmap
• rtabmapviz
• ros-teleop
• gazebo
• rviz

Launch

Change to the catkin_ws directory and source the ROS Melodic environment:

cd /mnt/Workspaces/RoboND-Map-My-World/catkin_ws
source devel/setup.bash

Launch commands for SLAM:

roslaunch my_robot world.launch

rosrun teleop_twist_keyboard teleop_twist_keyboard.py

roslaunch my_robot mapping.launch

The map will be re-created everytime this is launched. We can find the map in the maps sub directory.

Launch command for visualizing the map

rtabmap-databaseViewer /mnt/Workspaces/RoboND-Map-My-World/catkin_ws/src/my_robot/maps/rtabmap.db

Launch commands for Localization

roslaunch my_robot localization.launch

Real Time Visulization

• Another tool that we can use is rtabmapviz, which is an additional node for real time visualization of feature mapping, loop closures, and more.
• It’s not recommended to use this tool while mapping in simulation due to the computing overhead.
• rtabmapviz is great to deploy on a real robot during live mapping to ensure that we are getting the necessary features to complete loop closures.

To enable this visualization in this project, the mapping.launch file needs to be uncommented for the node rtabmapviz.