follow_path_example_launch.py

# Copyright (c) 2021 Samsung Research America
#
# 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 pathlib import Path
import tempfile
 
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.actions import (AppendEnvironmentVariable, DeclareLaunchArgument, ExecuteProcess,
                            IncludeLaunchDescription, OpaqueFunction, RegisterEventHandler)
from launch.conditions import IfCondition
from launch.event_handlers import OnShutdown
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.substitutions import Command, LaunchConfiguration, PythonExpression
from launch_ros.actions import Node
 
 
def generate_launch_description() -> LaunchDescription:
    nav2_bringup_dir = get_package_share_directory('nav2_bringup')
    sim_dir = get_package_share_directory('nav2_minimal_tb4_sim')
    desc_dir = get_package_share_directory('nav2_minimal_tb4_description')
 
    robot_sdf = os.path.join(desc_dir, 'urdf', 'standard', 'turtlebot4.urdf.xacro')
    world = os.path.join(sim_dir, 'worlds', 'depot.sdf')
    map_yaml_file = os.path.join(nav2_bringup_dir, 'maps', 'depot.yaml')
 
    # Launch configuration variables
    use_rviz = LaunchConfiguration('use_rviz')
    headless = LaunchConfiguration('headless')
 
    # Declare the launch arguments
    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)'
    )
 
    # start the simulation
    world_sdf = tempfile.mktemp(prefix='nav2_', suffix='.sdf')
    world_sdf_xacro = ExecuteProcess(
        cmd=['xacro', '-o', world_sdf, ['headless:=', headless], world])
    start_gazebo_server_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(get_package_share_directory('ros_gz_sim'), 'launch',
                         'gz_sim.launch.py')),
        launch_arguments={'gz_args': ['-r -s ', world_sdf]}.items())
 
    remove_temp_sdf_file = RegisterEventHandler(event_handler=OnShutdown(
        on_shutdown=[
            OpaqueFunction(function=lambda _: os.remove(world_sdf))
        ]))
 
    set_env_vars_resources = AppendEnvironmentVariable(
            'GZ_SIM_RESOURCE_PATH',
            os.path.join(sim_dir, 'worlds'))
    start_gazebo_client_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(get_package_share_directory('ros_gz_sim'),
                         'launch',
                         'gz_sim.launch.py')
        ),
        condition=IfCondition(PythonExpression(
            ['not ', headless])),
        launch_arguments={'gz_args': ['-v4 -g ']}.items(),
    )
 
    spawn_robot_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(sim_dir, 'launch', 'spawn_tb4.launch.py')),
        launch_arguments={'use_sim_time': 'True',
                          'robot_sdf': robot_sdf,
                          'x_pose': '-8.0',
                          'y_pose': '0.0',
                          'z_pose': '0.0',
                          'roll': '0.0',
                          'pitch': '0.0',
                          'yaw': '0.0'}.items())
 
    start_robot_state_publisher_cmd = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        name='robot_state_publisher',
        output='screen',
        parameters=[
            {'use_sim_time': True, 'robot_description': Command(['xacro', ' ', robot_sdf])}
        ]
    )
 
    # start the visualization
    rviz_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(nav2_bringup_dir, 'launch', 'rviz_launch.py')
        ),
        condition=IfCondition(use_rviz),
        launch_arguments={'namespace': ''}.items(),
    )
 
    # start navigation
    bringup_cmd = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            os.path.join(nav2_bringup_dir, 'launch', 'bringup_launch.py')
        ),
        launch_arguments={'map': map_yaml_file}.items(),
    )
 
    # start the demo autonomy task
    demo_cmd = Node(
        package='nav2_simple_commander',
        executable='example_follow_path',
        emulate_tty=True,
        output='screen',
    )
 
    set_env_vars_resources2 = AppendEnvironmentVariable(
            'GZ_SIM_RESOURCE_PATH',
            str(Path(os.path.join(desc_dir)).parent.resolve()))
 
    ld = LaunchDescription()
    ld.add_action(declare_use_rviz_cmd)
    ld.add_action(declare_simulator_cmd)
    ld.add_action(world_sdf_xacro)
    ld.add_action(remove_temp_sdf_file)
    ld.add_action(set_env_vars_resources)
    ld.add_action(set_env_vars_resources2)
    ld.add_action(start_gazebo_server_cmd)
    ld.add_action(start_gazebo_client_cmd)
    ld.add_action(spawn_robot_cmd)
    ld.add_action(start_robot_state_publisher_cmd)
    ld.add_action(rviz_cmd)
    ld.add_action(bringup_cmd)
    ld.add_action(demo_cmd)
    return ld