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Mapping and Navigation with Turtlebot

Introduction

(Originally from this post from RTAB-Map's forum)

This page will show how to use rtabmap with navigation stack on a Turtlebot3.

Requirements:

# Noetic:
sudo apt install ros-noetic-rtabmap-demos ros-noetic-turtlebot3-simulations ros-noetic-turtlebot3-navigation ros-noetic-dwa-local-planner 

Usage:

export TURTLEBOT3_MODEL=waffle
roslaunch turtlebot3_gazebo turtlebot3_world.launch

export TURTLEBOT3_MODEL=waffle
roslaunch rtabmap_demos demo_turtlebot3_navigation.launch

Autonomous Navigation

When a map is created (in mapping mode or localization mode), you can then follow the same steps from 2.3.2 of the Autonomous Navigation of a Known Map with TurtleBot tutorial to navigate in the map.

Normally, you only have to "drop" a navigation goal on the map with RVIZ to see the robot moving autonomously to it. Click on "2D Nav Goal" button in RVIZ to set a goal. You should see a planned path (red line) like this to the goal set (green arrow):

The commands sent by move_base:

$ rostopic echo /mobile_base/commands/velocity

Localization mode

After a mapping session as above, a database is saved here ~/.ros/rtabmap.db. Now restart the demo_turtlebot3_navigation.launch with argument localization:=true:

 $ roslaunch rtabmap_demos demo_turtlebot3_navigation.launch localization:=true

Move the robot around until it can relocalize in the previous map, then the 2D map would re-appear again when a loop closure is found.

Issues

• On autonomous navigation, if teleop node is also sending commands on the same topic as move_base at the same time, the robot may not move.

• If there are many TF warnings, you can try to increase robot_state_publisher's publishing frequency in turtlebot_bringup/launch/includes/robot.launch.xml from 5 to 10 Hz. You can also increase wait_for_transform argument of demo_turtlebot_mapping.launch to 0.2.

• If sometimes the robot is planning a straight path through an obstacle, it may be related to this issue. This can be fixed by using rtabmap_costmap_plugins::StaticLayer instead of costmap_2d::StaticLayer here.