loopback_simulation.launch.py

# Copyright (c) 2024 Open Navigation LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
 
import os
 
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import LifecycleNode
from launch_ros.descriptions import ParameterFile
from nav2_common.launch import RewrittenYaml
 
 
def generate_launch_description() -> LaunchDescription:
    bringup_dir = get_package_share_directory('nav2_bringup')
    namespace = LaunchConfiguration('namespace')
    declare_namespace_cmd = DeclareLaunchArgument(
        'namespace',
        default_value='',
        description='Top-level namespace',
    )
 
    params_file = LaunchConfiguration('params_file')
    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',
    )
 
    scan_frame_id = LaunchConfiguration('scan_frame_id')
    declare_scan_frame_id_cmd = DeclareLaunchArgument(
        'scan_frame_id',
        default_value='base_scan',
    )
 
    remappings = [('/tf', 'tf'), ('/tf_static', 'tf_static')]
 
    configured_params = ParameterFile(
        RewrittenYaml(
            source_file=params_file,
            root_key=namespace,
            param_rewrites={},
            convert_types=True,
        ),
        allow_substs=True,
    )
 
    loopback_sim_cmd = LifecycleNode(
        package='nav2_loopback_sim',
        executable='loopback_simulator',
        name='loopback_simulator',
        namespace=namespace,
        output='screen',
        autostart=True,
        parameters=[
            configured_params,
            {'scan_frame_id': scan_frame_id, 'use_sim_time': True},
        ],
        remappings=remappings,
    )
 
    ld = LaunchDescription()
    ld.add_action(declare_namespace_cmd)
    ld.add_action(declare_scan_frame_id_cmd)
    ld.add_action(declare_params_file_cmd)
    ld.add_action(loopback_sim_cmd)
    return ld