Slam learning notes - build a complete gazebo multi machine simulation slam from scratch (4)

introduction

To the last chapter of this tutorial , We used a single robot before SLAM, Multi robot map fusion SLAM, And the navigation of multiple robots in the map . The last chapter （ There may be new chapters later , This is the end of the first series ）, We will use explore_lite Function pack , Make the robot in the process of drawing , Autonomously has established the frontier most suitable for expansion in the map , And automatic edge navigation , Edge construction map , Until the whole map is built .
The source code in gitee On , You can see the first article .

The overall launch file

It mainly integrates the contents of lesson 2 and lesson 3 , On multiple machines slam Added move_base Navigation , recycling explore_lite Publish coordinates

<launch>
    <!--SLAM Algorithm  -->
    <arg name="slam_method" default="gmapping"/>
    <arg name="simulation" default="true"/>
    <arg name="move_forward_only" default="false"/>

    <group if="$(arg simulation)" >
        <!--  Open the simulation world  -->
        <include file="$(find gazebo_tutorials)/launch/create_world.launch" />
         <!--  Place the robot  -->
        <include file="$(find gazebo_tutorials)/launch/place_robot.launch">
            <arg name="robot_x_pos" value="0.0"/>
            <arg name="robot_y_pos" value="0.0"/>
            <arg name="robot_z_pos" value="0.0"/>
            <arg name="robot_yaw" value="0.0"/>
            <arg name="robot_name" value="tb3_0"/>
        </include>
         <!--  Place the robot  -->
        <include file="$(find gazebo_tutorials)/launch/place_robot.launch">
            <arg name="robot_x_pos" value="-3"/>
            <arg name="robot_y_pos" value="0.0"/>
            <arg name="robot_z_pos" value="0.0"/>
            <arg name="robot_yaw" value="0.0"/>
            <arg name="robot_name" value="tb3_1"/>
        </include>
    </group>
    <!--  Turn on SLAM -->
    <include file="$(find gazebo_tutorials)/slam_methods/$(arg slam_method).launch">
        <arg name="ns" value="tb3_0"/>
    </include>
    <include file="$(find gazebo_tutorials)/slam_methods/$(arg slam_method).launch">
        <arg name="ns" value="tb3_1"/>
    </include>

    <!--  Start the map fusion node and join 1 Robot map information  -->
     <include file="$(find gazebo_tutorials)/launch/map_merging.launch">
        <arg name="if_first_robot" value="True"/>
        <arg name="robot_x_pos" value="0.0"/>
        <arg name="robot_y_pos" value="0.0"/>
        <arg name="robot_z_pos" value="0.0"/>
        <arg name="robot_name" value="tb3_0"/>
    </include>
    <!--  Join in 2 Robot map information  -->
    <include file="$(find gazebo_tutorials)/launch/map_merging.launch">
        <arg name="if_first_robot" value="False"/>
        <arg name="robot_x_pos" value="-3"/>
        <arg name="robot_y_pos" value="0.0"/>
        <arg name="robot_z_pos" value="0.0"/>
        <arg name="robot_name" value="tb3_1"/>
    </include>   

    <!-- move_base Navigation -->
    <include file="$(find gazebo_tutorials)/launch/move_base.launch">
        <arg name="ns" value="tb3_0" />
        <arg name="move_forward_only" value="$(arg move_forward_only)"/>
    </include> 
        <include file="$(find gazebo_tutorials)/launch/move_base.launch">
        <arg name="ns" value="tb3_1" />
        <arg name="move_forward_only" value="$(arg move_forward_only)"/>
    </include> 

    <!--  Explore on your own  -->
    <include file="$(find gazebo_tutorials)/launch/explore_costmap.launch">
        <arg name="ns" value="tb3_0" />
    </include>
    <include file="$(find gazebo_tutorials)/launch/explore_costmap.launch">
        <arg name="ns" value="tb3_1" />
    </include>

    <!-- rviz -->
    <include file="$(find gazebo_tutorials)/launch/rviz_two_robots.launch" />
</launch>

explore_costmap.launch

This function package is to calculate the edge of the grid map , Then calculate the weight of the edge by some means , Decide where to expand . This is not a self-contained Feature Pack , Download it yourself .

sudo apt-get install ros-melodic-explore-lite

Mainly costmap_topic and costmap_updates_topic Two parameters , The map they receive will determine what they navigate based on .

<launch>
<arg name="ns" default="tb3_0"/>

<node pkg="explore_lite" type="explore" respawn="false" name="$(arg ns)_explore" output="screen">
  <remap from="move_base_simple/goal" to="$(arg ns)/move_base_simple/goal"/>
  <remap from="move_base" to="$(arg ns)/move_base"/>
    
  <param name="robot_base_frame" value="$(arg ns)/base_footprint"/>
  <param name="costmap_topic" value="$(arg ns)/map"/>
  <param name="costmap_updates_topic" value="$(arg ns)/map_updates"/>
  <!-- Specifies whether to publish visual boundaries -->
  <param name="visualize" value="true"/>  
  <!-- Calculate the new boundary and reconsider the frequency of the target （Hz）-->
  <param name="planner_frequency" value="0.33"/>
  <!-- Time is in seconds . When the robot is  progress_timeout  When there is no progress , The current goal will be abandoned .-->
  <param name="progress_timeout" value="30.0"/>
  <!-- For weighted boundary . This multiplication parameter affects the leading edge potential component of the leading edge weight （ The distance to the front ）.-->
  <param name="potential_scale" value="3.0"/>
  <!-- For weighted boundary . This multiplication parameter affects the leading edge direction component of the leading edge weight . This parameter does not currently perform any operation , For forward compatibility only .-->
  <param name="orientation_scale" value="0.0"/>
  <!-- For weighted boundary . This multiplication parameter affects the boundary weight （ Boundary size ） The boundary gain component of .-->
  <param name="gain_scale" value="1.0"/>
  <!-- The transformation tolerance used when changing the robot posture .-->
  <param name="transform_tolerance" value="0.3"/>
  <!-- Consider the boundary as the minimum size of the boundary of the exploration target . In meters .-->
  <param name="min_frontier_size" value="0.1"/>
</node>
</launch>

start-up

Last command roslaunch gazebo_tutorials two_robots_autoslam.launch Start it up .
stay rviz You can add MarkerArray To show the leading edge of the map
Finally, we can see that the two robots move by themselves , And maps are integrated , But very stupid , After all, this function package is prepared for a robot , I may find a way to write the decision-making program of multiple robots later , Coming soon .