TurtleBot3 的 ROS2 运行框架梳理 2 - SLAM

这里主要使用 cartographer 进行建图.


ros2 launch turtlebot3_bringup robot.launch.py ## 加载 底盘以及lidar 部件.
ros2 run turtlebot3_teleop teleop_keyboard ## 加载手动遥控控制部分.

//默认位置为坐标 0, 0, 0 位置, 所以需要做地图之前进行规划和起始走位.
ros2 launch turtlebot3_cartographer cartographer.launch.py ## 启用 cartographer 的算法处理
根据以往建图经验, 尽量保持机器人平稳走动, 尤其不宜急停/急转. 速度为200mm/s 30度/s 为宜. lidar的视角做好超过180, 位置走一遍为宜. 否则多次扫描有大几率造成重影问题, 毕竟软件算法做到回环矫正还是比较难的.

ros2 run nav2_map_server map_saver -f ~/map  ## 保存地图, 产生 map.pgm/yaml文件.

下一步进行 地图手动修正.
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详细步骤

import os
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch_ros.actions import Node
from launch.substitutions import LaunchConfiguration
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch.substitutions import ThisLaunchFileDir

def generate_launch_description():
    use_sim_time = LaunchConfiguration('use_sim_time', default='false')
    turtlebot3_cartographer_prefix = get_package_share_directory('turtlebot3_cartographer')
    cartographer_config_dir = LaunchConfiguration('cartographer_config_dir',
                                                    default=os.path.join(turtlebot3_cartographer_prefix, 'config'))
    configuration_basename = LaunchConfiguration('configuration_basename', default='turtlebot3_lds_2d.lua')  //激光雷达的参数以及建图参数

    resolution = LaunchConfiguration('resolution', default='0.05')  ## 地图分辨率
    publish_period_sec = LaunchConfiguration('publish_period_sec', default='1.0') ##地图更新发布频率, 最好不要太快, 会影响CPU计算速度.

    rviz_config_dir = os.path.join(get_package_share_directory('turtlebot3_cartographer'), 'rviz', 'tb3_cartographer.rviz')

    return LaunchDescription([
        DeclareLaunchArgument(
            'cartographer_config_dir',
            default_value=cartographer_config_dir,
            description='Full path to config file to load'),
        DeclareLaunchArgument(
            'configuration_basename',
            default_value=configuration_basename,
            description='Name of lua file for cartographer'),
        DeclareLaunchArgument(
            'use_sim_time',
            default_value='false',
            description='Use simulation (Gazebo) clock if true'),

        Node(
            package='cartographer_ros',
            node_executable='cartographer_node',
            node_name='cartographer_node',
            output='screen',
            parameters=[{'use_sim_time': use_sim_time}],
            arguments=['-configuration_directory', cartographer_config_dir, '-configuration_basename', configuration_basename]),

        DeclareLaunchArgument(
            'resolution',
            default_value=resolution,
            description='Resolution of a grid cell in the published occupancy grid'),

        DeclareLaunchArgument(
            'publish_period_sec',
            default_value=publish_period_sec,
            description='OccupancyGrid publishing period'),

        IncludeLaunchDescription(
            PythonLaunchDescriptionSource([ThisLaunchFileDir(), '/occupancy_grid.launch.py']),
            launch_arguments={'use_sim_time': use_sim_time, 'resolution': resolution, 'publish_period_sec': publish_period_sec}.items(),
        ),

        Node(
            package='rviz2',
            node_executable='rviz2',
            node_name='rviz2',
            arguments=['-d', rviz_config_dir],
            parameters=[{'use_sim_time': use_sim_time}],
            output='screen'),
    ])

//occupancy_grid.launch.py  地图局部计算,回环等处理部分.

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch_ros.actions import Node
from launch.substitutions import LaunchConfiguration

def generate_launch_description():
    use_sim_time = LaunchConfiguration('use_sim_time', default='false')
    resolution = LaunchConfiguration('resolution', default='0.05')
    publish_period_sec = LaunchConfiguration('publish_period_sec', default='1.0')

    return LaunchDescription([
        DeclareLaunchArgument(
            'resolution',
            default_value=resolution,
            description='Resolution of a grid cell in the published occupancy grid'),

        DeclareLaunchArgument(
            'publish_period_sec',
            default_value=publish_period_sec,
            description='OccupancyGrid publishing period'),

        DeclareLaunchArgument(
            'use_sim_time',
            default_value='false',
            description='Use simulation (Gazebo) clock if true'),

        Node(
            package='cartographer_ros',
            node_executable='occupancy_grid_node',
            node_name='occupancy_grid_node',
            output='screen',
            parameters=[{'use_sim_time': use_sim_time}],
            arguments=['-resolution', resolution, '-publish_period_sec', publish_period_sec]),
    ])