概述

笔记本电脑为ubuntu18.04，其上已经安装了ROS1(melodic)，现预切换为ROS2来测试下建图是否有隐患。所以在ROS1基础上安装了ROS2，并在ROS2上安装cartographer以测试建图效果。

1.安装ROS2

电脑中本身已经具备ROS1，现在其基础上安装ROS2，选择版本为eloquent。

1）安装python3及colcon

$ sudo apt install -y libpython3-dev python3-pip
$ pip3 install -U argcomplete
$ sudo apt-get install python3-colon-common-extensions

2） 添加ROS2的源

$ sudo apt update && sudo apt install curl gnupg2 lsb-release
$ curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -
$ sudo sh -c 'echo "deb [arch=amd64] http://packages.ros.org/ros2/ubuntu bionic main" > /etc/apt/sources.list.d/ros2-latest.list'

3）安装eloquent桌面版本

$ sudo apt update
$ sudo apt install ros-eloquent-desktop

ros2的安装要比ros1快很多。

4）修改~/.bashrc

为了使ROS1与ROS2共存，在.bashrc中删除了之前对ROS1设置的环境变量，如下所示:

source /opt/ros/melodic/setup.bash
source ~/**_ws/devel/setup.bash

2 安装cartographer及cartographer_ros

1） 安装cartographer

  采用二进制的方式，如下：

$ sudo apt-get install ros-eloquent-cartographer

2) 安装cartographer_ros

  采用二进制的方式，如下：

$ sudo apt-get install ros-eloquent-cartographer-ros

此安装的路径为/opt/ros/eloquent/cartographer
/opt/ros/eloquent/cartographer_ros

3. 测试cartographer

   由于在之前使用ros1时录制了激光雷达scan、惯导imu、里程计odom、静态TF的数据，所以想着直接拿过来在ROS2中使用。

1） 创建launch启动文件

   在ROS2中launch文件为python编写的。我们需要切换到cartographer_ros的安装路径然后创建launch文件。

$  cd /opt/ros/eloquent/cartographer_ros
$  sudo mkdir -p launch &&  cd launch
$  sudo vi car_cartographer.launch.py

其内容如下:

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='true')
    cartographer_prefix = get_package_share_directory('cartographer_ros')
    cartographer_config_dir = LaunchConfiguration('cartographer_config_dir', default=os.path.join(
                                                  cartographer_prefix, 'configuration_files'))
    configuration_basename = LaunchConfiguration('configuration_basename',
                                                 default='ucar_2d.lua')
 
    resolution = LaunchConfiguration('resolution', default='0.05')
    publish_period_sec = LaunchConfiguration('publish_period_sec', default='1.0')
 
    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',
            parameters=[{'use_sim_time': use_sim_time}],
            output='screen'),
    ])

该启动文件中启动了cartographer_ros 、生成栅格地图的occupancy_grid.launch.py节点以及rviz2，同时还加载了一些参数项，如cartographer的配置文件"ucar_2d.lua"(与ROS1中相同),"/use_sim_time"、“publishe_period_sec”等。可以看出其未设置传感器的话题名称。

下面需要创建occupancy_grid.launch.py 以及ucar_2d.lua。

2） 创建栅格地图生成节点occupancy_grid.launch.py

其目录与1）中创建的启动文件相同

$  sudo vi occupancy_grid.launch.py

内容如下：

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]),
    ])

3） 创建配置文件ucar_2d.lua

   和ROS1相同，配置文件也存在于configuration_files目录下，其目录下已经存在一些示例文件，我们在其中创建我们自定义的配置文件。

$  cd /opt/ros/eloquent/cartographer_ros/configuration_files
$  sudo vi ucar_2d.lua

内容如下:

include "map_builder.lua"
include "trajectory_builder.lua"

options = {
 map_builder = MAP_BUILDER,
 trajectory_builder = TRAJECTORY_BUILDER,
 map_frame = "map",
 tracking_frame = "base_link",
 published_frame = "base_link",
 odom_frame = "odom",
 provide_odom_frame = true,
 publish_frame_projected_to_2d = true,
 --use_pose_extrapolator = false,
 use_odometry = false,
 use_nav_sat = false,
 use_landmarks = false,
 num_laser_scans = 1,
 num_multi_echo_laser_scans = 0,
 num_subdivisions_per_laser_scan = 1,
 num_point_clouds = 0,
 lookup_transform_timeout_sec = 0.2,
 submap_publish_period_sec = 0.3,
 pose_publish_period_sec = 5e-3,
 trajectory_publish_period_sec = 30e-3,
 rangefinder_sampling_ratio = 1.,
 odometry_sampling_ratio = 1.,
 fixed_frame_pose_sampling_ratio = 1.,
 imu_sampling_ratio = 1.,
 landmarks_sampling_ratio = 1.,
}

MAP_BUILDER.use_trajectory_builder_2d = true

TRAJECTORY_BUILDER_2D.min_range = 0.3
TRAJECTORY_BUILDER_2D.max_range = 10
TRAJECTORY_BUILDER_2D.missing_data_ray_length =10.
TRAJECTORY_BUILDER_2D.use_imu_data = false
TRAJECTORY_BUILDER_2D.use_online_correlative_scan_matching = true 
TRAJECTORY_BUILDER_2D.motion_filter.max_angle_radians = math.rad(0.1)

POSE_GRAPH.constraint_builder.min_score = 0.65
POSE_GRAPH.constraint_builder.global_localization_min_score = 0.7

return options

在这里我们不使用IMU和里程计，先使用激光来进行建图测试，所有配置文件中设置的tracking_frame和published_frame均为base_link。

以上我们将建图侧的准备工作做好了，下一步准确bag包，然后启动建图就可以了。

4）准备bag包数据并播放

如上所描述，我们的bag包为ROS1的，ROS2下想用也可以，需要使用ros2bag进行启动。首先安装ros2中相关的bag库

$  sudo apt-get install ros-eloquent-ros-ros2bag*  ros-eloquent-ros-rosbag_v2*

然后新建终端，先设置ROS的环境为ROS1即melodic。再设置为ROS2的eloquent，最后再用ros2的bag play来进行播放。在播放前不需要像ROS1一样设置/use_sim_time参数。

$ source /opt/ros/melodic/setup.bash
$ source /opt/ros/eloquent/setup.bash
$ ros2 bag play -s rosbag_v2 ~/tydk_without_odom.bag

5）启动建图指令

之后启动建图指令即可，新建一个终端

$ source /opt/ros/eloquent/setup.bash
$ ros2 launch cartographer_ros ucar_cartographer_ros.launch.py

6） 效果展示

两个终端，一个进行bag播放，一个进行建图，会弹出rviz界面，在其中添加/map、/PointCloud2插件即可。效果如下所示：

参考：
[1]: https://blog.csdn.net/fanshuaifang/article/details/114399792
[2]: https://www.guyuehome.com/35570