ROS2教程(8) - 在ROS中使用launch、launch替换文件 - Linux

创建launch文件

编写launch文件

mkdir launch

• launch/turtlesim_mimic_launch.xml

<launch>
  <node pkg="turtlesim" exec="turtlesim_node" name="sim" namespace="turtlesim1"/>
  <node pkg="turtlesim" exec="turtlesim_node" name="sim" namespace="turtlesim2"/>
  <node pkg="turtlesim" exec="mimic" name="mimic">
    <remap from="/input/pose" to="/turtlesim1/turtle1/pose"/>
    <remap from="/output/cmd_vel" to="/turtlesim2/turtle1/cmd_vel"/>
  </node>
</launch>

// 启动两个乌龟窗口，让一只乌龟模仿另一只乌龟的动作
// 在不同的工作空间启动两个turtlesim节点
// 最后一个节点也来自turtlesim包，但是是不同的执行文件:mimic。此节点进行了重映射，这意味着mimic将订阅/turtlesim1/sim的位姿信息，并将其重新发布给/turtlesim2/sim。换句话说，turtlesim2将模仿turtlesim1的动作。

run

# 终端1
cd launch && ros2 launch turtlesim_mimic_launch.xml
# 终端2
ros2 topic pub -r 1 /turtlesim1/turtle1/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 2.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: -1.8}}"
# 终端3
rqt_graph

# 除了直接运行启动文件之外，还可以运行由包提供的文件
ros2 launch <package_name> <launch_file_name>
# 在package.xml添加依赖项
<exec_depend>ros2launch</exec_depend>

将launch文件集成到ROS中

crate pkg

mkdir -p launch_ws/src
cd launch_ws/src
ros2 pkg create --build-type ament_cmake --license Apache-2.0 cpp_launch_example

CMakeLists.txt

# Install launch files.
install(DIRECTORY
  launch
  DESTINATION share/${PROJECT_NAME}/
)

launch

• launch/my_script_launch.xml

<launch>
  <node pkg="demo_nodes_cpp" exec="talker" name="talker"/>
</launch>

run

# build
colcon build
# run
ros2 launch cpp_launch_example my_script_launch.xml

替换

crate pkg

ros2 pkg create --build-type ament_cmake --license Apache-2.0 launch_tutorial
mkdir launch_tutorial/launch

CMakeLists.txt

# add
install(DIRECTORY
        launch
        DESTINATION share/${PROJECT_NAME}/
)

父launch文件

• launch/example_main.launch.yaml

launch:
  - let:
      name: 'background_r'
      value: '200'
  - include:
      file: '$(find-pkg-share launch_tutorial)/launch/example_substitutions.launch.yaml'
      arg:
        - name: 'turtlesim_ns'
          value: 'turtlesim2'
        - name: 'use_provided_red'
          value: 'True'
        - name: 'new_background_r'
          value: '$(var background_r)'

替换launch文件

• launch/example_substitutions.launch.yaml

launch:
  - arg:
      name: 'turtlesim_ns'
      default: 'turtlesim1'
  - arg:
      name: 'use_provided_red'
      default: 'False'
  - arg:
      name: 'new_background_r'
      default: '200'

  - node:
      pkg: 'turtlesim'
      namespace: '$(var turtlesim_ns)'
      exec: 'turtlesim_node'
      name: 'sim'
  - executable:
      cmd: 'ros2 service call $(var turtlesim_ns)/spawn turtlesim/srv/Spawn "{x: 5, y: 2, theta: 0.2}"'
  - executable:
      cmd: 'ros2 param set $(var turtlesim_ns)/sim background_r 120'
  - timer:
      period: 2.0
      children:
        - executable:
            cmd: 'ros2 param set $(var turtlesim_ns)/sim background_r $(var new_background_r)'
            if: '$(eval "$(var new_background_r) == 200 and $(var use_provided_red)")'

run

colcon build

# 启动父launch文件
ros2 launch launch_tutorial example_main.launch.yaml

# 查看替换launch文件参数
ros2 launch launch_tutorial example_substitutions.launch.yaml --show-args

# 启动替换launch文件
ros2 launch launch_tutorial example_substitutions.launch.yaml turtlesim_ns:='turtlesim3' use_provided_red:='True' new_background_r:=200

原文地址：https://blog.csdn.net/2301_79695159/article/details/140589196

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