ROS2系列教程：AMCL定位与地图

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输入：/scan + /tf(odom→base_link) + 静态地图（/map）
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输出：/amcl_pose（位姿估计）+ /particlecloud（粒子可视化）+ TF（map→odom）

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from launch_ros.actions import Node
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from launch_ros.actions import LifecycleNode
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# 生命周期节点（map_server 必须是 LifecycleNode）
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map_server = LifecycleNode(
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    package='nav2_map_server',
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    executable='map_server',
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    name='map_server',
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    output='screen',
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    parameters=[{'yaml_filename': map_yaml, 'use_sim_time': True}])
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# 生命周期管理器（自动 configure + activate）
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lifecycle_manager = Node(
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    package='nav2_lifecycle_manager',
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    executable='lifecycle_manager',
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    name='lifecycle_manager_map',
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    output='screen',
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    parameters=[{'autostart': True,
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                 'node_names': ['map_server']}])

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amcl:
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  ros__parameters:
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    use_sim_time: True
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    alpha1: 0.2        # 旋转噪声
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    alpha2: 0.2        # 平移噪声
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    alpha3: 0.2        # 平移导致旋转的噪声
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    alpha4: 0.2        # 旋转导致平移的噪声
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    alpha5: 0.2        # 速度噪声
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    base_frame_id: "base_link"
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    global_frame_id: "map"
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    odom_frame_id: "odom"
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    max_particles: 2000      # 最大粒子数
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    min_particles: 500       # 最小粒子数
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    resample_interval: 1     # 每 N 帧重采样
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    save_pose_rate: 0.5      # 保存位姿频率
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    sigma_hit: 0.2           # 激光命中噪声
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    laser_min_range: 0.1
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    laser_max_range: 10.0
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    laser_max_beams: 60      # 每帧激光使用的束数
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    min_particles_for_kld: 500
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    transform_tolerance: 1.0
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    update_min_a: 0.2        # 最小旋转角才更新
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    update_min_d: 0.25       # 最小平移距离才更新
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    z_hit: 0.5               # 命中概率权重
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    z_max: 0.05              # 超距概率权重
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    z_rand: 0.5              # 随机概率权重
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    z_short: 0.05            # 短距离概率权重

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from launch import LaunchDescription
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from launch_ros.actions import Node, LifecycleNode
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from launch_ros.actions import SetParameter
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import os
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from ament_index_python.packages import get_package_share_directory
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def generate_launch_description():
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    pkg_bringup = get_package_share_directory('my_robot_bringup')
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    map_yaml = os.path.join(pkg_bringup, 'maps', 'my_map.yaml')
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    amcl_params = os.path.join(pkg_bringup, 'config', 'amcl_params.yaml')
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    map_server = LifecycleNode(
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        package='nav2_map_server', executable='map_server',
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        name='map_server', output='screen',
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        parameters=[{'yaml_filename': map_yaml, 'use_sim_time': True}])
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    amcl = LifecycleNode(
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        package='nav2_amcl', executable='amcl',
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        name='amcl', output='screen',
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        parameters=[amcl_params])
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    lifecycle_manager = Node(
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        package='nav2_lifecycle_manager', executable='lifecycle_manager',
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        name='lifecycle_manager_localization', output='screen',
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        parameters=[{'autostart': True,
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                     'node_names': ['map_server', 'amcl']}])
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    rviz = Node(package='rviz2', executable='rviz2',
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                arguments=['-d', os.path.join(pkg_bringup, 'config', 'localization.rviz')],
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                output='screen')
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    return LaunchDescription([
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        SetParameter(name='use_sim_time', value=True),
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        map_server, amcl, lifecycle_manager, rviz,
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    ])