Nav2极简笔记03-启动文件launch

回顾一下，tb3_simulation_launch.py :

      """This is all-in-one launch script intended for use by nav2 developers."""
      import os
      from ament_index_python.packages import get_package_share_directory
      from launch import LaunchDescription
      from launch.actions import DeclareLaunchArgument, ExecuteProcess, IncludeLaunchDescription
      from launch.conditions import IfCondition
      from launch.launch_description_sources import PythonLaunchDescriptionSource
      from launch.substitutions import LaunchConfiguration, PythonExpression
      from launch_ros.actions import Node
      def generate_launch_description():
         # Get the launch directory
          bringup_dir = get_package_share_directory('nav2_bringup')
          launch_dir = os.path.join(bringup_dir, 'launch')
         # Create the launch configuration variables
          slam = LaunchConfiguration('slam')
          namespace = LaunchConfiguration('namespace')
          use_namespace = LaunchConfiguration('use_namespace')
          map_yaml_file = LaunchConfiguration('map')
          use_sim_time = LaunchConfiguration('use_sim_time')
          params_file = LaunchConfiguration('params_file')
          default_bt_xml_filename = LaunchConfiguration('default_bt_xml_filename')
          autostart = LaunchConfiguration('autostart')
         # Launch configuration variables specific to simulation
          rviz_config_file = LaunchConfiguration('rviz_config_file')
          use_simulator = LaunchConfiguration('use_simulator')
          use_robot_state_pub = LaunchConfiguration('use_robot_state_pub')
          use_rviz = LaunchConfiguration('use_rviz')
          headless = LaunchConfiguration('headless')
          world = LaunchConfiguration('world')
         # Map fully qualified names to relative ones so the node's namespace can be prepended.
         # In case of the transforms (tf), currently, there doesn't seem to be a better alternative
         # https://github.com/ros/geometry2/issues/32
         # https://github.com/ros/robot_state_publisher/pull/30
         # TODO(orduno) Substitute with `PushNodeRemapping`
         # https://github.com/ros2/launch_ros/issues/56
          remappings = [('/tf', 'tf'),
                        ('/tf_static', 'tf_static')]
         # Declare the launch arguments
          declare_namespace_cmd = DeclareLaunchArgument(
             'namespace',
              default_value='',
              description='Top-level namespace')
          declare_use_namespace_cmd = DeclareLaunchArgument(
             'use_namespace',
              default_value='false',
              description='Whether to apply a namespace to the navigation stack')
          declare_slam_cmd = DeclareLaunchArgument(
             'slam',
              default_value='False',
              description='Whether run a SLAM')
          declare_map_yaml_cmd = DeclareLaunchArgument(
             'map',
              default_value=os.path.join(bringup_dir, 'maps', 'turtlebot3_world.yaml'),
              description='Full path to map file to load')
          declare_use_sim_time_cmd = DeclareLaunchArgument(
             'use_sim_time',
              default_value='true',
              description='Use simulation (Gazebo) clock if true')
          declare_params_file_cmd = DeclareLaunchArgument(
             'params_file',
              default_value=os.path.join(bringup_dir, 'params', 'nav2_params.yaml'),
              description='Full path to the ROS2 parameters file to use for all launched nodes')
          declare_bt_xml_cmd = DeclareLaunchArgument(
             'default_bt_xml_filename',
              default_value=os.path.join(
                  get_package_share_directory('nav2_bt_navigator'),
                 'behavior_trees', 'navigate_w_replanning_and_recovery.xml'),
              description='Full path to the behavior tree xml file to use')
          declare_autostart_cmd = DeclareLaunchArgument(
             'autostart', default_value='true',
              description='Automatically startup the nav2 stack')
          declare_rviz_config_file_cmd = DeclareLaunchArgument(
             'rviz_config_file',
              default_value=os.path.join(bringup_dir, 'rviz', 'nav2_default_view.rviz'),
              description='Full path to the RVIZ config file to use')
          declare_use_simulator_cmd = DeclareLaunchArgument(
             'use_simulator',
              default_value='True',
              description='Whether to start the simulator')
          declare_use_robot_state_pub_cmd = DeclareLaunchArgument(
             'use_robot_state_pub',
              default_value='True',
              description='Whether to start the robot state publisher')
          declare_use_rviz_cmd = DeclareLaunchArgument(
             'use_rviz',
              default_value='True',
              description='Whether to start RVIZ')
          declare_simulator_cmd = DeclareLaunchArgument(
             'headless',
              default_value='False',
              description='Whether to execute gzclient)')
          declare_world_cmd = DeclareLaunchArgument(
             'world',
             # TODO(orduno) Switch back once ROS argument passing has been fixed upstream
             # https://github.com/ROBOTIS-GIT/turtlebot3_simulations/issues/91
             # default_value=os.path.join(get_package_share_directory('turtlebot3_gazebo'),
             # 'worlds/turtlebot3_worlds/waffle.model'),
              default_value=os.path.join(bringup_dir, 'worlds', 'waffle.model'),
              description='Full path to world model file to load')
         # Specify the actions
          start_gazebo_server_cmd = ExecuteProcess(
              condition=IfCondition(use_simulator),
              cmd=['gzserver', '-s', 'libgazebo_ros_init.so', world],
              cwd=[launch_dir], output='screen')
          start_gazebo_client_cmd = ExecuteProcess(
              condition=IfCondition(PythonExpression([use_simulator, ' and not ', headless])),
              cmd=['gzclient'],
              cwd=[launch_dir], output='screen')
          urdf = os.path.join(bringup_dir, 'urdf', 'turtlebot3_waffle.urdf')
          start_robot_state_publisher_cmd = Node(
              condition=IfCondition(use_robot_state_pub),
              package='robot_state_publisher',
              executable='robot_state_publisher',
              name='robot_state_publisher',
              namespace=namespace,
              output='screen',
              parameters=[{'use_sim_time': use_sim_time}],
              remappings=remappings,
              arguments=[urdf])
          rviz_cmd = IncludeLaunchDescription(
              PythonLaunchDescriptionSource(os.path.join(launch_dir, 'rviz_launch.py')),
              condition=IfCondition(use_rviz),
              launch_arguments={'namespace': '',
                               'use_namespace': 'False',
                               'rviz_config': rviz_config_file}.items())
          bringup_cmd = IncludeLaunchDescription(
              PythonLaunchDescriptionSource(os.path.join(launch_dir, 'bringup_launch.py')),
              launch_arguments={'namespace': namespace,
                               'use_namespace': use_namespace,
                               'slam': slam,
                               'map': map_yaml_file,
                               'use_sim_time': use_sim_time,
                               'params_file': params_file,
                               'default_bt_xml_filename': default_bt_xml_filename,
                               'autostart': autostart}.items())
         # Create the launch description and populate
          ld = LaunchDescription()
         # Declare the launch options
          ld.add_action(declare_namespace_cmd)
          ld.add_action(declare_use_namespace_cmd)
          ld.add_action(declare_slam_cmd)
          ld.add_action(declare_map_yaml_cmd)
          ld.add_action(declare_use_sim_time_cmd)
          ld.add_action(declare_params_file_cmd)
          ld.add_action(declare_bt_xml_cmd)
          ld.add_action(declare_autostart_cmd)
          ld.add_action(declare_rviz_config_file_cmd)
          ld.add_action(declare_use_simulator_cmd)
          ld.add_action(declare_use_robot_state_pub_cmd)
          ld.add_action(declare_use_rviz_cmd)
          ld.add_action(declare_simulator_cmd)
          ld.add_action(declare_world_cmd)
         # Add any conditioned actions
          ld.add_action(start_gazebo_server_cmd)
          ld.add_action(start_gazebo_client_cmd)
         # Add the actions to launch all of the navigation nodes
          ld.add_action(start_robot_state_publisher_cmd)
          ld.add_action(rviz_cmd)
          ld.add_action(bringup_cmd)
         return ld
  
 

如果需要一边导航和建图同步开展，设置参数slam:=True；

ros2 launch nav2_bringup tb3_simulation_launch.py slam:=True

这时不用给初始位置，直接导航即可，机器人会同步绘制地图。 

换一个环境（可以任意换，这里以house为例）： 

修改（tb3_sim_house.py）：

          declare_world_cmd = DeclareLaunchArgument(
             'world',
             # TODO(orduno) Switch back once ROS argument passing has been fixed upstream
             # https://github.com/ROBOTIS-GIT/turtlebot3_simulations/issues/91
             # default_value=os.path.join(get_package_share_directory('turtlebot3_gazebo'),
             # 'worlds/turtlebot3_worlds/waffle.model'),
              default_value=os.path.join(bringup_dir, 'worlds', 'waffle_house.model'),
              description='Full path to world model file to load')
  
 

waffle_house.model

         <model name="turtlebot3_house">
           <static>1</static>
           <include>
             <uri>model://turtlebot3_house</uri>
           </include>
         </model>
  
 

编译后，使用如下命令：

• ros2 launch nav2_bringup tb3_sim_house.py slam:=True

注意，house入口处的障碍物-信箱📫，来导航算法不给力，扛起来！！！

不玩了，正常建图和导航效果如下：

比自己遥控省时省力。

重要的功能包：

• turtlebot3
• navigation2
• slam_toolbox 

更多功能自己摸索一下。

roslaunch2示例

节点加载

      from launch import LaunchDescription
      from launch_ros.actions import Node
      def generate_launch_description():
         return LaunchDescription([
              Node(
                  name='node_runtime_name',
                  package='ros2_package_name',
                  executable='name_of_executable',
                  parameters=[{'name_of_int_param': 1,
                              'name_of_str_param': 'value'}],
                  remappings=[('from', 'to')],
                  output='screen',
              ),
             # More Nodes!
          ])
  
 

加载参数yaml

      node_name:
        ros__parameters:
            some_int_param: 1
            some_str_param: "the_value"
  
 

更具体一点：

      from ament_index_python.packages import get_package_share_directory
      # Assuming you have a file called package_name/config/params.yaml
      node_params = os.path.join(
          get_package_share_directory('package_name'),
         'config',
         'params.yaml'
      )
      # Add this to your LaunchDescription
      Node(
          name='node_runtime_name',
          package='ros2_package_name',
          executable='name_of_executable',
          parameters=[{'another_param': 42.0},
                       node_params]
      )
  
 

包含其他launch文件

      import os
      from ament_index_python.packages import get_package_share_directory
      from launch.actions import IncludeLaunchDescription
      from launch.launch_description_sources import PythonLaunchDescriptionSource
      # Assuming you have a file called package_name/launch/my_launch.launch.py
      my_launch_file = os.path.join(
          get_package_share_directory('package_name'),
         'launch',
         'my_launch.launch.py'
      )
      # Add this to your LaunchDescription
      IncludeLaunchDescription(
          PythonLaunchDescriptionSource([my_launch_file])
      ),
  
 

加载URDF文件：

      import os
      from ament_index_python.packages import get_package_share_directory
      from launch_ros.actions import Node
      # Load the URDF into a parameter
      desc_dir = get_package_share_directory('robot_description_pkg')
      urdf_path = os.path.join(desc_dir, 'robots', 'my_urdf.urdf')
      urdf = open(urdf_path).read()
      # Add this to your LaunchDescription
      Node(
          name='robot_state_publisher',
          package='robot_state_publisher',
          executable='robot_state_publisher',
          parameters=[{'robot_description': urdf}],
      )
  
 

文章来源: zhangrelay.blog.csdn.net，作者：zhangrelay，版权归原作者所有，如需转载，请联系作者。

原文链接：zhangrelay.blog.csdn.net/article/details/119931907