Can't launch nav2_bringup. Error: No such file or directory: ''

[arad2456]

I want to call nav2_bringup in my launch file. I use ros2 humble. When I make the call I get the error message:

arad2456:~/ros2_ws$ ros2 launch slam_train slam_algorithm.launch.py
[INFO] [launch]: All log files can be found below /home/arad2456/.ros/log/2024-03-18-02-17-32-921054-LAPTOP-HALVVF48-24760
[INFO] [launch]: Default logging verbosity is set to INFO
[ERROR] [launch]: Caught exception in launch (see debug for traceback): [Errno 2] No such file or directory: ''

Without the call for nav2_bringup in the launch file it gets launched without problems. When I add the call for nav2_bringup and run it in debug I get:

arad2456:~/ros2_ws$` ros2 launch --debug slam_train slam_algorithm.launch.py
[DEBUG] [launch.launch_context]: emitting event synchronously: 'launch.events.IncludeLaunchDescription'
[INFO] [launch]: All log files can be found below /home/arad2456/.ros/log/2024-03-18-02-17-01-363420-LAPTOP-HALVVF48-24214
[INFO] [launch]: Default logging verbosity is set to DEBUG
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7f4afb07d270>'
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7f4afb07d270>' ✓ '<launch.event_handlers.on_include_launch_description.OnIncludeLaunchDescription object at 0x7f4afb07cfa0>'
Executing <Task finished name='Task-2' coro=<LaunchService._process_one_event() done, defined at /opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py:228> exception=FileNotFoundError(2, 'No such file or directory') created at /opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py:318> took 0.903 seconds
[DEBUG] [launch]: An exception was raised in an async action/event
[DEBUG] [launch]: Traceback (most recent call last):
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 336, in run_async
    raise completed_tasks_exceptions[0]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 230, in _process_one_event
    await self.__process_event(next_event)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 250, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  [Previous line repeated 4 more times]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 38, in visit_all_entities_and_collect_futures
    sub_entities = entity.visit(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/action.py", line 108, in visit
    return self.execute(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/actions/node.py", line 490, in execute
    self._perform_substitutions(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/actions/node.py", line 445, in _perform_substitutions
    evaluated_parameters = evaluate_parameters(context, self.__parameters)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/utilities/evaluate_parameters.py", line 159, in evaluate_parameters
    output_params.append(param.evaluate(context))
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/parameter_descriptions.py", line 235, in evaluate
    param_file = perform_substitutions(context, self.__param_file)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/perform_substitutions_impl.py", line 26, in perform_substitutions
    return ''.join([context.perform_substitution(sub) for sub in subs])
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/perform_substitutions_impl.py", line 26, in <listcomp>
    return ''.join([context.perform_substitution(sub) for sub in subs])
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_context.py", line 240, in perform_substitution
    return substitution.perform(self)
  File "/opt/ros/humble/local/lib/python3.10/dist-packages/nav2_common/launch/rewritten_yaml.py", line 88, in perform
    data = yaml.safe_load(open(yaml_filename, 'r'))
FileNotFoundError: [Errno 2] No such file or directory: ''

[ERROR] [launch]: Caught exception in launch (see debug for traceback): [Errno 2] No such file or directory: ''
[DEBUG] [launch.launch_context]: emitting event: 'launch.events.Shutdown'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afade3d00>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afac4fc10>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afaad0520>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afaad0be0>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afac72c20>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afaad2320>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afae0bb50>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7f4afccc3430>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7f4afb07f340>' 

My launch file is:

import os
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch import actions
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.substitutions import LaunchConfiguration, Command
import launch_ros

def generate_launch_description():

    pkg_share = launch_ros.substitutions.FindPackageShare(package='slam_train').find('slam_train')
    pkg_gazebo_ros = get_package_share_directory('gazebo_ros')
    path_lafette = os.path.join(pkg_share, 'urdf', 'Lafette_small_urdf.urdf')

    world = os.path.join(get_package_share_directory('turtlebot3_gazebo'), 'worlds', 'turtlebot3_house.world')
    #world = os.path.join(os.environ['HOME'], '.gazebo', 'models', 'factory', 'factory.model')
    #world = os.path.join(pkg_share, 'worlds', 'baylands.world')

    declare_use_sim_time = actions.DeclareLaunchArgument(name='use_sim_time', default_value='true', description='Use simulation (Gazebo) clock if true')

    declare_model_urdf = actions.DeclareLaunchArgument(name='model', default_value=path_lafette, description='Absolute path to robot urdf file')

    robot_state_publisher_node = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description': Command(['xacro ', LaunchConfiguration('model')])}]
    )

    joint_state_publisher_node = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
        name='joint_state_publisher',
        parameters=[{'use_sim_time' : LaunchConfiguration('use_sim_time')}]
    )

    gzserver_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(pkg_gazebo_ros, 'launch', 'gzserver.launch.py')
        ),
        launch_arguments={'world': world}.items()
    )

    gzclient_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(pkg_gazebo_ros, 'launch', 'gzclient.launch.py')
        )
    )

    spawn_entity = launch_ros.actions.Node(
        package='gazebo_ros',
        executable='spawn_entity.py',
        arguments=[
            '-entity', 'Lafette',
            '-topic', 'robot_description',
            '-x', '-1.8',  # X position
            '-y', '0.0',  # Y position
            '-z', '0.0',  # Z position (usually 0 for ground-based robots)
            '-Y', '0.0'  # Yaw orientation (in radians; here, 1.57 radians equals 90 degrees)
            ],
        output='screen'
        )

    default_rviz_config_path = os.path.join(pkg_share, 'rviz/urdf_config.rviz')

       # Declare the launch argument
    declare_rviz_config = actions.DeclareLaunchArgument(name='rvizconfig', default_value=default_rviz_config_path, description='path to rviz config file')

    rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        name='rviz2',
        output='screen',
        arguments=['-d', LaunchConfiguration('rvizconfig')],
    )

    slam_toolbox_dir = os.path.join(get_package_share_directory('slam_toolbox'), 'launch')

    slam_toolbox_launch = IncludeLaunchDescription(PythonLaunchDescriptionSource(os.path.join(slam_toolbox_dir, 'online_async_launch.py')),
        launch_arguments={
            'slam_params_file': os.path.join(pkg_share, 'config_slam', 'mapper_params_online_async.yaml'),
            'use_sim_time': LaunchConfiguration('use_sim_time')
            }.items()
    )

    nav2_toolbox_dir = os.path.join(get_package_share_directory('nav2_bringup'), 'launch')

    nav2_toolbox_launch = IncludeLaunchDescription(PythonLaunchDescriptionSource(os.path.join(nav2_toolbox_dir, 'navigation_launch.py')),
        launch_arguments={'use_sim_time': LaunchConfiguration('use_sim_time')}.items()
    )

    ld = LaunchDescription()

    ld.add_action(declare_use_sim_time)
    ld.add_action(declare_model_urdf)
    ld.add_action(gzserver_cmd)
    ld.add_action(gzclient_cmd)
    ld.add_action(robot_state_publisher_node)
    ld.add_action(joint_state_publisher_node)
    ld.add_action(spawn_entity)
    ld.add_action(declare_rviz_config)
    ld.add_action(rviz_node)
    ld.add_action(slam_toolbox_launch)
    ld.add_action(nav2_toolbox_launch)

    return ld

[SteveMacenski]

Check out the standard inputs to the navigation launch file from our bringup package: https://github.com/ros-planning/navigation2/blob/main/nav2_bringup/launch/bringup_launch.py#L183

[arad2456]

Thanks! It works now.

[SteveMacenski]

No problemo