description.launch.py

import os

from launch_ros.actions import Node
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.substitutions import Command, LaunchConfiguration
from ament_index_python.packages import get_package_share_directory
    

def generate_launch_description():

    # Get package dirs
    package_dir = get_package_share_directory('hollander_description')

    # Default values
    default_model_path = os.path.join(package_dir, 'src/description/rollende_hollander.urdf')

    configurable_parameters = [
        {'name': 'model',     'default': default_model_path, 'description': 'Absolute path to robot urdf file'},
        {'name': 'namespace', 'default': 'hollander',        'description': 'Namespace to avoide conflicts'},
        {'name': 'log_level', 'default': 'info',             'description': 'debug log level [DEBUG|INFO|WARN|ERROR|FATAL]'},
       ]

    def declare_configurable_parameters(parameters):
        return [DeclareLaunchArgument(param['name'], default_value=param['default'], description=param['description']) for param in parameters]


    """ NODES """
    robot_state_publisher_node = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        name='robot_state_publisher',
        namespace=LaunchConfiguration("namespace"),
        parameters=[{'robot_description': Command(['xacro ', LaunchConfiguration('model')])}],
        arguments=['--ros-args', '--log-level', LaunchConfiguration('log_level')],
        emulate_tty=True,
    )

    joint_state_publisher_node = Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
        name='joint_state_publisher',
        namespace=LaunchConfiguration("namespace"),
        arguments=['--ros-args', '--log-level', LaunchConfiguration('log_level')],
        emulate_tty=True,
    )

    return LaunchDescription(declare_configurable_parameters(configurable_parameters) + [
        robot_state_publisher_node,
        joint_state_publisher_node,
    ])