ros2 launch file syntax error - XacroException: No such file or directory: + - InvalidFrontendLaunchFileError:

Question

I have an issue when trying to execute a python launch file. Whenever I execute the file I get the following error:

[INFO] [launch]: All log files can be found below /home/jonas/.ros/log/2024-03-03-11-26-59-235308-jonas-30810
[INFO] [launch]: Default logging verbosity is set to INFO
[ERROR] [launch]: Caught exception in launch (see debug for traceback): Caught multiple exceptions when trying to load file of format [py]:
 - XacroException: No such file or directory: ./mercury_description.urdf.xacro [Errno 2] No such file or directory: './mercury_description.urdf.xacro'
 - InvalidFrontendLaunchFileError: The launch file may have a syntax error, or its format is unknown

I already checked that xacro_file generates the correct path and corresponds to the path mercury_gazebo.urdf.xacro which is located in the share urdf folder. Here is the path (generated in xacro_file and this is the same for the actual file): /home/jonas/ros2_ws/install/tr_robot_description/share/tr_robot_description/urdf/mercury_gazebo.urdf.xacro

For the second error I don't have an idea what I have to check.

What could I try to resolve this issue?

Here is the complete launch file:

import os

from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch_ros.actions import Node
from launch.actions import ExecuteProcess, IncludeLaunchDescription, RegisterEventHandler
from launch.event_handlers import OnProcessExit
from launch.launch_description_sources import PythonLaunchDescriptionSource
import xacro


def generate_launch_description():

    mercury_description_path = os.path.join(
        get_package_share_directory('tr_robot_description'))

    xacro_file = os.path.join(mercury_description_path,
                              'urdf',
                              'mercury_gazebo.urdf.xacro') 

    doc = xacro.parse(open(xacro_file))
    xacro.process_doc(doc)
    robot_description_config = doc.toxml()
    robot_description = {'robot_description': robot_description_config}

    node_robot_state_publisher = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        output='screen',
        parameters=[robot_description]
    )

    spawn_entity = Node(package='gazebo_ros', executable='spawn_entity.py',
                        arguments=['-topic', 'robot_description',
                                   '-entity', 'robot'],
                        output='screen')

    joint_state_broadcaster_spawner = Node(
        package="controller_manager",
        executable="spawner",
        arguments=["joint_state_broadcaster",
                   "--controller-manager", "/controller_manager"],
    )

    robot_controller_spawner = Node(
        package="controller_manager",
        executable="spawner",
        arguments=["position_trajectory_controller", "-c", "/controller_manager"],
    )


    return LaunchDescription([
        RegisterEventHandler(
            event_handler=OnProcessExit(
                target_action=spawn_entity,
                on_exit=[joint_state_broadcaster_spawner],
            )
        ),
        RegisterEventHandler(
            event_handler=OnProcessExit(
                target_action=joint_state_broadcaster_spawner,
                on_exit=[robot_controller_spawner],
            )
        ),
        spawn_entity,
        node_robot_state_publisher,
    ])

Answer 1

Oh I maybe just saw the issue. I guess there is an issue in the mercury_gazebo.urdf.xacro

Adding $(find tr_robot_description)/urdf/ in front of every xacro include recolved all the xacro errors