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Launch
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本文由簡體中文內容確定性轉換，並受版本化術語表保護。
1.概述
rosbag2的作用是來序列化儲存資料的，是一個數據庫。
ros2 launch 功能包名 launch檔名
ros2 pkg create cpp01_launch --build-type ament_cmake --dependencies rclcpp
ros2 pkg create cpp01_launch --build-type ament_cmake --dependencies rclcpp
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
def generate_launch_description():
return LaunchDescription([])2.launch基本使用流程(C++)
配置完這個，不管我launch目錄下有多少launch檔案，只需要配置這一次就行了。
這樣說明我們cmake配置對了
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
def generate_launch_description():
return LaunchDescription([])
<launch>
<node pkg = "turtlesim" exec = "turtlesim_node" name = "t1" />
<node pkg = "turtlesim" exec = "turtlesim_node" name = "t2" />
</launch>
launch:
node:
pkg: "turtlesim"
exec: "turtlesim_node"
name: "t1"
node:
pkg: "turtlesim"
exec: "turtlesim_node"
name: "t2"
最好新增一個依賴
3.Launch_Python_Node
這個是標籤exec_name
這倆引數傳參的區別在於--ros-args的區別
在launch裡寫更簡單
這樣是等價的
{}裡是yaml格式的。
有另一種更常用的方法，就是上來讀取yaml檔案，把資料都存在yaml裡，用到的時候直接讀取。
把yaml檔案放到config裡
ros2 param dump haha --output-dir src/cpp01_launch/config/
還需要再配置cmakelists
我們要讀就讀install目錄下的。
直接複製路徑
可以進一步最佳化程式碼
這個就是來獲取某個功能包的share目錄路徑
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
import os
def generate_launch_description():
# turtle1 = Node(
# package="turtlesim",
# executable="turtlesim_node",
# exec_name="my_label",
# ros_arguments=["--remap","__ns:=/t2"]
# )
turtle2 = Node(
package="turtlesim",
executable="turtlesim_node",
name="haha",
parameters=[os.path.join(get_package_share_directory("cpp01_launch"),"config","haha.yaml")]
)
return LaunchDescription([turtle2])
建議採用第三種 動態獲取路徑
respawn是自動重啟的意思，這樣執行後的節點，你用滑鼠關閉小烏龜視窗後，也會自動重啟節點，再把小烏龜視窗開啟一個新的。
按Ctrl+C可以終止。
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
import os
def generate_launch_description():
# turtle1 = Node(
# package="turtlesim",
# executable="turtlesim_node",
# exec_name="my_label",
# ros_arguments=["--remap","__ns:=/t2"]
# )
turtle2 = Node(
package="turtlesim",
executable="turtlesim_node",
name="haha",
# parameters=[{"background_r": 255,"background_g": 0,"background_b": 0}],
# parameters=["/home/tungchiahui/mysource/ros2src/4.ws02_tools/install/cpp01_launch/share/cpp01_launch/config/haha.yaml"],
parameters=[os.path.join(get_package_share_directory("cpp01_launch"),"config","haha.yaml")],
respawn=True
)
return LaunchDescription([turtle2])
第一個是原話題名稱，第二個是新話題名稱
4.Launch_Python_執行命令
這是個列表，列表裡面寫我們的指令
這樣是把日誌既輸出到終端也輸出到日誌，如果不寫則只會輸出到日誌。
這樣就是把命令當成終端指令來執行
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
def generate_launch_description():
turtle = Node(
package="turtlesim",
executable="turtlesim_node"
)
cmd = ExecuteProcess(
cmd = ["ros2 topic echo /turtle1/pose"],
output = "both",
shell = True
)
return LaunchDescription([turtle,cmd])
如果指令過長，可以分到多個字串裡執行。
這樣也是可以執行的。
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
def generate_launch_description():
turtle = Node(
package="turtlesim",
executable="turtlesim_node"
)
cmd = ExecuteProcess(
cmd = [FindExecutable(name="ros2"),"topic","echo","/turtle1/pose"],
output = "both",
shell = True
)
return LaunchDescription([turtle,cmd])
5.Launch_Python_引數設定
沒傳值的話，烏龜紅色是滿的，那就是粉紅色背景
也可以傳值，比如傳backg_r:=0
這樣背景色就變的更偏藍綠了。
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
def generate_launch_description():
bg_r = DeclareLaunchArgument(name="backg_r",default_value="255")
bg_g = DeclareLaunchArgument(name="backg_g",default_value="255")
bg_b = DeclareLaunchArgument(name="backg_b",default_value="255")
turtle = Node(
package="turtlesim",
executable="turtlesim_node",
parameters=[{"background_r" : LaunchConfiguration("backg_r"),"background_g" : LaunchConfiguration("backg_g"),"background_b" : LaunchConfiguration("backg_b")}]
)
return LaunchDescription([bg_r,bg_g,bg_b,turtle])6.Launch_Python_檔案包含
假設我要編寫一個機器人啟動相關的launch檔案，在這個launch檔案中，我可能要啟動雷達，啟動IMU，啟動底盤等等，我們需要把這些launch檔案都包含進機器人啟動的launch檔案中。
這個值是由被包含的launch檔案封裝而來的物件。
這個物件對應的類就是PythonLaunchDescriptionSource，
類裡面還得設定一個引數。
這個引數是launch_file_path就是檔案路徑。
建議用這個來獲取路徑。
也可以為其傳參
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
import os
def generate_launch_description():
include = IncludeLaunchDescription(
launch_description_source=PythonLaunchDescriptionSource(
launch_file_path=os.path.join(
get_package_share_directory("cpp01_launch"),
"launch/py",
"py04_args_launch.py"
)
),
launch_arguments=[("backg_r","80"),("backg_g","10"),("backg_b","200")]
)
return LaunchDescription([include])7.Launch_Python_分組設定
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
def generate_launch_description():
turtle1 = Node(
package="turtlesim",
executable="turtlesim_node",
name="t1"
)
turtle2 = Node(
package="turtlesim",
executable="turtlesim_node",
name="t2"
)
turtle3 = Node(
package="turtlesim",
executable="turtlesim_node",
name="t3"
)
group1 = GroupAction(actions=[PushRosNamespace("g1"),turtle1,turtle2])
group2 = GroupAction(actions=[PushRosNamespace("g2"),turtle3])
return LaunchDescription([group1,group2])8.Launch_Python_事件設定
第一個主要用於註冊事件，第二個是開始事件，第三個是節點退出。
這個是在終端中生成新小烏龜的命令
第一個引數是針對哪個事件進行註冊。
target_action是事件源，你要為哪個節點註冊事件。
on_start是等到事件被觸發，你要做哪些操作？
from launch import LaunchDescription
from launch_ros.actions import Node
封装终端指令相关类
from launch.actions import ExecuteProcess
from launch.substitutions import FindExecutable
参数声明与获取
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
文件包含相关
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
分组相关
from launch_ros.actions import PushRosNamespace
from launch.actions import GroupAction
事件相关
from launch.event_handlers import OnProcessStart,OnProcessExit
from launch.actions import ExecuteProcess,RegisterEventHandler,LogInfo
获取功能包下share目录或路径
from ament_index_python.packages import get_package_share_directory
def generate_launch_description():
turtle = Node(
package="turtlesim",
executable="turtlesim_node",
)
spawn = ExecuteProcess(
cmd=["ros2 service call /spawn turtlesim/srv/Spawn \"{'x': 8.0,'y': 3.0}\""],
output="both",
shell=True
)
event_start = RegisterEventHandler(
event_handler=OnProcessStart(
target_action=turtle,
on_start=spawn
)
)
event_exit = RegisterEventHandler(
event_handler=OnProcessExit(
target_action=turtle,
on_exit=[LogInfo(msg="turtlesim_node:退出！")]
)
)
return LaunchDescription([turtle,event_start,event_exit])
on_exit可以建立一個物件，也可以放在列表裡。
可以只學Python版本的Launch，XML和Yaml版本的Launch可以瞭解就行，自己寫就寫Python版本的，當你要用到別人開源的功能包用的Launch是Xml或者yaml版本一般不影響正常使用。