9、RTAB-Map 3D mapping navigation

wiki：http://wiki.ros.org/rtabmap_ros

9.1、Introduction

This software package is the ROS function package of RTAB Map, which is an RGB-D SLAM method based on a global loop closure detector with real-time constraints. The software package can be used to generate a three-dimensional point cloud of the environment and create a two-dimensional occupancy grid map for navigation.

Start the command of the bottom layer, map building or navigation

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roslaunch transbot_nav transbot_bringup.launch lidar_type:=a1 # Astra + laser + Transbot
roslaunch transbot_nav astra_bringup.launch     # Astra + Transbot
roslaunch transbot_nav transbot_rtabmap.launch open_rviz:=False     # mapping 
roslaunch transbot_nav transbot_rtabmap_nav.launch open_rviz:=False # navigation

lidar_type parameter: the type of lidar used: [a1, a2, a3, s1, s2].

Note: Astra + laser + Transbot is the fusion of depth camera and lidar; Astra + Transbot refers to pure vision, mainly using the function package depthimage_to_laserscan to convert the depth image into lidar data (the scanning range is different from lidar), and its mapping function Same as lidar.

Start visualization

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roslaunch transbot_nav view_rtabmap.launch      # mapping visualization
roslaunch transbot_nav view_rtabmap_nav.launch  # navigation visualization

View tf tree

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rosrun rqt_tf_tree rqt_tf_tree  

Viewn node

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rqt_graph

Keyboard control node

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rosrun teleop_twist_keyboard teleop_twist_keyboard.py  # system integration

9.2、Navigation

After starting up according to the above method, you can choose any method to control the map creation (handle control is recommended); the slower the map creation, the better the effect (especially the angular speed); the robot is full of the area to be created.

• Handle control
• Keyboard control

When the map is completed, directly ctrl+c to exit the map node, the system will automatically save the map.

The default save path of the map is [~/.ros/rtabmap.db].

9.3、Navigation obstacle avoidance

Note: [R2] on the handle can cancel the target point.

When the navigation mode is turned on, the system automatically loads a 2D raster map, and cannot directly load a 3D map. It needs to be loaded manually.

Load the 3D map (1, 2, 3), 4 is to add the rviz debugging tool.

Steps for usage

• Place the robot at the origin and start the navigation function, the system will automatically match the position of the robot.

• Single-point navigation:

  Click the 【2D Nav Goal】 of the 【rviz】tool. Then use the mouse to select a target point on the map model where there are no obstacles. Release the mouse to start the navigation. Only one target point can be selected. Finally, robot car will move towards the target point form, after reaching the target point, the car will stop.

• Multi-point navigation:

  Click 【Publish Point】of the 【rviz】tool. Then select a target point where there are no obstacles on the map model, release the mouse to start navigation. You can click 【Publish Point】again, then select others point. Finally, robot car will cruise from point to point.

9.4、Node rtabmap

9.4.1、Subscribed Topics

9.4.2、Published Topics

9.4.3、Services

9.4.4、Parameters

9.4.5、tf transform

Preparation:

• base_link → sensor
• odom → base_link

Provide:

map → odom

9.5、Node rtabmapviz

This node starts the visualization interface of RTAB-Map. It is a wrapper for the RTAB-MapGUI library. Its purpose is the same as rviz, but with RTAB-Map specific options.

9.5.1、Subscribed Topics

9.5.2、Parameters

9.5.3、Required tf Transforms

• base_link →Sensor coordinate system
• odom → base_link
• map → odom