Nav2极简笔记03-启动文件launch

Posted 2021-09-12 zhangrelay

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}],
)

---