7 RTAB-Map 3D mapping navigation

wiki: http://wiki.ros.org/rtabmap_ros

7.1 Introduction

This package is a ROS functional package for RTAB Map, an RGB-D SLAM method based on a global loop closure detector with real-time constraints. This package can be used to generate 3D point clouds of the environment and create 2D occupancy grid maps for navigation.

As can be seen from the above figure, there is no need for Monte Carlo positioning amcl, and RTAB Map has its own positioning function; if it is used, it will cause repeated positioning and positioning failure. When using RTAB Map to navigate the core framework, the initialized map is provided by RTAB Map, not map_server.

7.2 Mapping use

Note: When building a map, the slower the speed, the better the effect(note that if the rotation speed is slower), the effect will be poor if the speed is too fast.

According to different models, you only need to set the purchased model in [.bashrc], X1(ordinary four-wheel drive) X3(Mike wheel) X3plus(Mike wheel mechanical arm) R2(Ackerman differential) and so on. Section takes X3 as an example

Open the [.bashrc] file

sudo vim .bashrc 

Find the [ROBOT_TYPE] parameter and modify the corresponding model

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export  ROBOT_TYPE=X3    # ROBOT_TYPE: X1 X3 X3plus R2 X7 

7.2.1 Start

Start the underlying driver command(robot side)

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roslaunch  yahboomcar_nav  laser_astrapro_bringup.launch 

Command to start mapping or navigation(robot side)

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roslaunch  yahboomcar_nav  yahboomcar_rtabmap.launch  use_rviz:=False 

• use_rviz parameter: whether to open rviz.

Start Visualization(Virtual Machine)

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roslaunch  yahboomcar_nav  view_rtabmap.launch 

Keyboard control node(virtual machine)

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rosrun teleop_twist_keyboard teleop_twist_keyboard.py  # system integration 
roslaunch yahboomcar_ctrl yahboom_keyboard.launch      # yahboomcar custom 

7.2.2 Mapping

After starting up according to the above method, choose any method to control the map(handle control is recommended); the slower the speed when building the map, the better the effect(especially the angular speed); the robot fills the area to be built, and the map is closed as much as possible.

• 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 map save path [~/.ros/rtabmap.db].

View tf tree

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rosrun rqt_tf_tree rqt_tf_tree 

Node view

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rqt_graph 

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

7.3 Navigation and obstacle avoidance

Note: [R2] of the remote control handle has the function of canceling the target point.

Start the underlying driver command(robot side)

x
roslaunch yahboomcar_nav laser_astrapro_bringup.launch

Command to start mapping or navigation(robot side)

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roslaunch yahboomcar_nav yahboomcar_rtabmap_nav.launch use_rviz:=False 

• use_rviz parameter: whether to open rviz.

Start Visualization(Virtual Machine)

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roslaunch yahboomcar_nav view_rtabmap_nav.launch 

Keyboard control node(virtual machine)

x
rosrun teleop_twist_keyboard teleop_twist_keyboard.py  # system integration 
roslaunch yahboomcar_ctrl yahboom_keyboard.launch      # yahboomcar custom 

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

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

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

7.3.1 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 position of the actual car.
• Click the [2D Nav Goal] of the [rviz] tool, and then select the target point on the map where there are no obstacles, release the mouse to start the navigation, only one target point can be selected, and it will stop when it arrives.

7.3.2 Multi-point navigation

• Same as the first step of single-point navigation, first set the initial pose of the car.
• Click the [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 the navigation, you can click the [Publish Point] again, and then select the point, the robot will point and point cruising in between.
• 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.

7.3.3 Parameter configuration

After starting the navigation function, open the dynamic parameter adjustment tool, adjust it according to your own needs, and observe the motion state of the robot until the effect is optimal, record the current parameters, and modify them to the corresponding dwa_local_planner_params.yaml file under the yahboomcar_nav function package.

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rosrun rqt_reconfigure rqt_reconfigure 

Looking at the yahboomcar_navigation.launch file, you can see that the navigation parameters are modified in the move_base.launch file under the yahboomcar_rtabmap_nav function package.

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< launch > 
    <!-- Whether to open rviz || Whether to open rviz --> 
    < arg  name = "use_rviz"  default = "false" /> 
    <!-- MarkerArray node--> 
    < node  name = 'send_mark'  pkg = "yahboomcar_nav"  type = "send_mark.py" /> 
    <!-- Mobile APP Node--> 
    < include  file = "$(find yahboomcar_nav)/launch/library/app.launch" /> 
    <!-- Navigation core component move_base --> 
    < include  file = "$(find yahboomcar_nav)/launch/library/move_base.launch" /> 
    <!-- rtabmap navigation --> 
    < include  file = "$(find yahboomcar_nav)/launch/library/rtabmap_nav.launch" /> 
    <!-- RVIZ --> 
    < include  file = "$(find yahboomcar_nav)/launch/view/view_rtabmap_nav.launch"  if = "$(arg use_rviz)" /> 
</ launch > 

Find the move_base.launch file, open the sample file as follows, you can modify and replace it according to your needs; at this time, the [DWA planner] is selected, and the [DWA] file is loaded.

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< launch > 
    < arg  name = "robot_type"  value = "$(env ROBOT_TYPE)"  doc = "robot_type [X1,X3,X3plus,R2,X7]" /> 
    <!-- Arguments --> 
    < arg  name = "move_forward_only"  default = "false" /> 
    <!-- move_base --> 
    < node  pkg = "move_base"  type = "move_base"  respawn = "false"  name = "move_base"  output = "screen" > 
        < rosparam  file = "$(find yahboomcar_nav)/param/common/global_costmap_params.yaml"  command = "load" /> 
        < rosparam  file = "$(find yahboomcar_nav)/param/common/local_costmap_params.yaml"  command = "load" /> 
        < rosparam  file = "$(find yahboomcar_nav)/param/common/move_base_params.yaml"  command = "load" /> 
        < rosparam  file = "$(find yahboomcar_nav)/param/common/costmap_common_params_$(arg robot_type).yaml"  command = "load" 
            ns = "global_costmap" /> 
        < rosparam  file = "$(find yahboomcar_nav)/param/common/costmap_common_params_$(arg robot_type).yaml"  command = "load" 
            ns = "local_costmap" /> 
        < rosparam  file = "$(find yahboomcar_nav)/param/common/dwa_local_planner_params_$(arg robot_type).yaml"  command = "load" /> 
        < param  name = "base_local_planner"  type = "string"  value = "dwa_local_planner/DWAPlannerROS"  if = "$(eval arg('robot_type') == 'X3')" /> 
        <!-- <param name="base_local_planner" type="string" value="teb_local_planner/TebLocalPlannerROS"/>--> 
        < param  name = "DWAPlannerROS/min_vel_x"  value = "0.0"  if = "$(arg move_forward_only)" /> 
        < remap  from = "cmd_vel"  to = "cmd_vel" /> 
        < remap  from = "odom"  to = "odom" /> 
    </ node > 
</ launch > 

Note: When using the DWA planner, the difference between the omnidirectional car and the differential car is whether the speed in the Y direction is 0. There are clear comments in it, which can be modified according to the actual situation.

Enter the dwa_local_planner_params.yaml file under the yahboomcar_nav function package, some parameters are as follows:

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DWAPlannerROS : 
  # Robot Configuration Parameters 
  # The absolute value of the maximum linear velocity in the x direction, unit: m/s 
  # The maximum y velocity for the robot in m/s 
  max_vel_x :  0.6 
  # The absolute value of the minimum linear velocity in the x direction, a negative number means that it can be moved back, unit: m/s 
  # The minimum x velocity for the robot in m/s, negative for backwards motion. 
  min_vel_x : - 0.6 
  # The absolute value of the maximum linear velocity in the y direction, unit: m/s. Differential robot is 0 
  # The maximum y velocity for the robot in m/s 
  max_vel_y : 0.3 
  # The absolute value of the minimum linear velocity in the y direction, unit: m/s. Differential robot is 0 
  # The minimum y velocity for the robot in m/s 
  min_vel_y : - 0.3 
 … 
  # The limit acceleration of the robot in the x direction, the unit is meters/sec^2 
  # The x acceleration limit of the robot in meters/sec^2 
  acc_lim_x :  10.0 
  # The limit acceleration of the robot in the y direction, it is 0 for the differential robot 
  # The y acceleration limit of the robot in meters/sec^2 
  acc_lim_y : 10.0 
... .. 

Other parameter files can be opened, combined with annotations and courseware, and modified according to their own needs.

7.4 node rtabmap

This is the master node for this package. It is a wrapper around the RTAB mapping core library. Here, the map is incrementally built and optimized when loop closures are detected. The online output of the node is the local map, which contains the most recent 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].

7.4.1 Subscription topic

7.4.2 Post topic

7.4.3 Services

7.4.4 Parameters

7.4.5 tf conversion

what is needed:

• base_link → sensor
• odom → base_link

which provided:

map → odom

7.5 node rtabmapviz

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

7.5.1. Subscription topic

7.5.2 parameter configuration

7.5.3 the required tf conversion

• base_link → sensor coordinate system
• odom → base_link
• map → odom