ROS Basics - use the launch file (I) - start multiple ROS nodes in batch

ROS Basics - Use launch file ( One ) - Batch launch multiple ROS node

This paper mainly introduces launch Basic use of documents , The details of the launch Document format description and Pass on ROS Parameters param Methods , See ： https://aduandniuniu.blog.csdn.net/article/details/125181523?spm=1001.2014.3001.5502

roslaunch The command can be used to start the definition in launch（ start-up ） Nodes in the file .
roslaunch The order in which nodes start is not guaranteed , Because it is impossible to know from the outside when to initialize the node completely , Therefore, all the startup code must be able to start in any order ..

Command format ：

roslaunch [package] [filename.launch]

1、 newly build ROS engineering

$ mkdir -p ~/launchExample/src  
$ cd ~/launchExample/src 
$ catkin_init_workspace   // Initialize workspace 

$ catkin_create_pkg launchTest1 roscpp  // establish ROS Project package （pachage）
$ catkin_create_pkg launchTest2 roscpp  // establish ROS Project package （pachage）

$ mkdir launch            // establish .launch File storage directory 
$ cd ~/launchExample/  
$ catkin_make 

2、 newly build test.launch file

newly build ~/launchExample/launch/test.launch file , The contents are as follows ：

<launch>
    <node pkg="launchTest1" type="launchTest1_node" name="launchTest1_node" output="screen" args="" />
    <node pkg="launchTest2" type="launchTest1_node" name="launchTest2_node" output="screen" args="" />
</launch>

Be careful ： Among them type Field , To match the , CMakelist.txt in add_executable designated ROS The procedure is consistent .

3 Write test code

3.1 newly build launchTest1 The test program

newly build ~/launchExample/launchTest1/main.cpp file , The contents are as follows ：

void main()
{
printf(“Hello LaunchTest1”);
}

3.2 newly build launchTest2 The test program

newly build ~/launchExample/launchTest2/main.cpp file , The contents are as follows ：

void main()
{
printf(“Hello LaunchTest2”);
}

$ cd ~/launchExample/  
$ catkin_make 
$ source devel/setup.bash // Set up the operating environment 

4、roslaunch Command to start ROS node

4.1 Starting method 1

roslaunch test.launch  // Don't specify ROS Package path 

4.2 Starting method 2

catkin_create_pkg launchStart roscpp  // establish ROS Project package （pachage）
cp ~/launchExample/launch/test.launch ~/launchExample/launchStart/
roslaunch launchStart test.launch  // Appoint ROS Package path 

5 launch File format - Example 1

<launch>
    <node pkg="turtlesim" name="sim1" type="turtlesim_node"/>
    <node pkg="turtlesim" name="sim2" type="turtlesim_node"/>
</launch>

<launch>

  <group ns="turtlesim1">
    <node pkg="turtlesim" name="sim" type="turtlesim_node"/>
  </group>

  <group ns="turtlesim2">
    <node pkg="turtlesim" name="sim" type="turtlesim_node"/>
  </group>

  <node pkg="turtlesim" name="mimic" type="mimic">
    <remap from="input" to="turtlesim1/turtle1"/>
    <remap from="output" to="turtlesim2/turtle1"/>
  </node>

</launch>