10.RTAB 3D mapping and navigation

The following workspace contains the function packages in the entire rplidar_ws. If you need to transplant it to your own development board, you need to copy all the function packages to the src of the workspace for compilation, and install the relevant environment.

Note: This course uses Rosmaster-X3 as an example. It needs to be run with a depth camera. Rosmaster-X3 is run with an Astrapro depth camera.

Function package path: ~/rplidar_ws/src/yahboomcar_nav

10.1 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.

As can be seen from the above figure, Monte Carlo positioning amcl is not required. RTAB Map has its own positioning function; if used, it will cause repeated positioning and positioning failure. When using the RTAB Map navigation core framework, the initialized map is provided by RTAB Map, not map_server.

10.2 Mapping and Use

Input following command:

roslaunch yahboomcar_nav laser_astrapro_bringup.launch
roslaunch yahboomcar_nav yahboomcar_rtabmap.launch use_rviz:=true

• use_rviz parameter: whether to open rviz.

Keyboard control car:

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roslaunch yahboomcar_ctrl yahboom_keyboard.launch

After starting according to the above method, choose any one method to control the mapping;

The slower the speed when constructing the map, the better the effect (especially the angular speed); the robot fills the area to be mapped and the map is as closed as possible.

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].

View tf tree:

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rosrun rqt_tf_tree rqt_tf_tree

View node:

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rqt_graph

As can be seen from the above figure, the information that the [rtabmap] node needs to subscribe to: radar data, camera data, and tf data.

10.3 Navigation and obstacle avoidance

Input the following command to start the underlying driver:

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roslaunch yahboomcar_nav laser_astrapro_bringup.launch

Input the following command to start mapping or navigation:

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roslaunch yahboomcar_nav yahboomcar_rtabmap_nav.launch use_rviz:=False

• use_rviz parameter: whether to open rviz.

Keyboard control node:

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roslaunch yahboomcar_ctrl yahboom_keyboard.launch

When the navigation mode is turned on, the system automatically loads the 2D raster map.

It cannot directly load the 3D map and needs to be loaded manually.

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

At this time, you can manually add [MarkerArray] to facilitate multi-point navigation and observation, and adjust [rviz] display parameters according to needs, such as the size of lidar points.

10.3.1 Single point navigation

• Use the [2D Pose Estimate] of the [rviz] tool to set the initial pose until the position of the car in the simulation is consistent with the actual position of the car.
• Click [2D Nav Goal] of the [rviz] tool, and then select a target point on the map where there are no obstacles. Release the mouse to start navigation. You can only select one target point and stop when you reach it.

10.3.2 Multi-point navigation

• Same as the first step of single-point navigation, first set the initial pose of the car.
• Click [Publish Point] of the [rviz] tool, and then select the target point on the map where there are no obstacles. Release the mouse to start navigation. You can click [Publish Point] again, and then select the point. The robot Will cruise between points.
• When using the [2D Pose Estimate] tool of the [rviz] tool to set the initial pose of the car, the multi-point navigation function is automatically canceled.

10.4 rtabmap node description

This is the master node for this package. It is a wrapper around the RTAB mapping core library. Here, when loop closure is detected, the map is incrementally built and optimized.

The node's online output is this map, which contains the latest data added to the map. The default location of the RTAB map database is [.ros/rtabmap.db], and the workspace is also set to [.ros].

10.4.1 Subscribed Topics

10.4.2 Published Topics

10.4.3 Services

7.4.4 Parameters

7.4.5 TF transform

• Preparation:

  • base_link → sensor
  • odom → base_link

  Provide:

  map → odom