ROS2入门教程-创建launch文件

ROS2入门教程-创建launch文件

说明：

• 介绍如何创建launch文件

步骤：

• 新建目录

mkdir ~/luanch 

• 新建文件

  cd ~/luanch
  touch turtlesim_mimic_launch.py

• 内容如下：

from launch import LaunchDescription
from launch_ros.actions import Node

def generate_launch_description():
    return LaunchDescription([
        Node(
            package='turtlesim',
            namespace='turtlesim1',
            executable='turtlesim_node',
            name='sim'
        ),
        Node(
            package='turtlesim',
            namespace='turtlesim2',
            executable='turtlesim_node',
            name='sim'
        ),
        Node(
            package='turtlesim',
            executable='mimic',
            name='mimic',
            remappings=[
                ('/input/pose', '/turtlesim1/turtle1/pose'),
                ('/output/cmd_vel', '/turtlesim2/turtle1/cmd_vel'),
            ]
        )
    ])

• 运行：

cd ~/luanch 
ros2 luanch turtlesim_mimic_launch.py

[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [turtlesim_node-1]: process started with pid [11714]
[INFO] [turtlesim_node-2]: process started with pid [11715]
[INFO] [mimic-3]: process started with pid [11716]

• 发布话题

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}}"

• 效果：

• rqt_graph查看节点调用

代码解析

• 导入launch和node包

from launch import LaunchDescription
from launch_ros.actions import Node

• 定义launch描述函数

def generate_launch_description():
   return LaunchDescription([

   ])

• 调用两个节点打开两个turtlesim

Node(
    package='turtlesim',
    namespace='turtlesim1',
    executable='turtlesim_node',
    name='sim'
),
Node(
    package='turtlesim',
    namespace='turtlesim2',
    executable='turtlesim_node',
    name='sim'
),

• 调用第三个节点，turtlesim2跟随turtlesim1的位置变化而变化

Node(
    package='turtlesim',
    executable='mimic',
    name='mimic',
    remappings=[
      ('/input/pose', '/turtlesim1/turtle1/pose'),
      ('/output/cmd_vel', '/turtlesim2/turtle1/cmd_vel'),
    ]
)