在先前已经完成了Cartographer离线建图，离线建图方案是，先在底盘主机中录制bag包，包括/scan、/odom、/tf话题，然后将bag包拷贝到从机中，也就是自己的电脑，然后用自己的电脑启动cartographer建图节点，建完图后将得到的pgm、pbstream等文件再拷贝到底盘主机中。这样就完成了离线建图任务，参考链接如下：
下面开始梳理Cartographer的实时建图问题。
roslaunch cartographer_ros demo_backpack_2d.launch bag_filename:=～/floor_12.bag
rosservice call /finish_trajectory 0
rosservice call /write_state "{filename: '${HOME}/Downloads/floor_12.pbstream'}"
rosrun cartographer_ros cartographer_pbstream_to_ros_map -map_filestem=/home/lyp/Downloads/floor_22 -pbstream_filename=/home/lyp/Downloads/floor_22.pbstream -resolution=0.05
注意bag使用绝对路径。
3.1 demo_backpack_2d.launch（离线）
<launch>
<param name="/use_sim_time" value="true" />
<include file="$(find cartographer_ros)/launch/backpack_2d.launch" />
<node name="rviz" pkg="rviz" type="rviz" required="true"
args="-d $(find cartographer_ros)/configuration_files/demo_2d.rviz" />
<node name="playbag" pkg="rosbag" type="play"
args="--clock $(arg bag_filename)" />
</launch>
修改：
1. 删除掉rviz。原因是底盘中没有接显示器，不能启动rviz界面。对于如何看到rviz界面，可以设置主从机单独打开rviz。
2. 删除掉了bag播放节点。原因是实时建图，直接接入机器人控制节点、激光雷达节点（/odom、/scan、/tf），不需要再播放bag。
3.2 demo_backpack_2d.launch（实时）
<launch>
<param name="/use_sim_time" value="false" />
<include file="$(find cartographer_ros)/launch/backpack_2d.launch" />
只需要关注 launch/backpack_2d.launch文件。
<launch>
<param name="robot_description"
textfile="$(find cartographer_ros)/urdf/backpack_2d.urdf" />
<node name="robot_state_publisher" pkg="robot_state_publisher"
type="robot_state_publisher" />
<node name="cartographer_node" pkg="cartographer_ros"
type="cartographer_node" args="
-configuration_directory $(find cartographer_ros)/configuration_files
-configuration_basename backpack_2d.lua"
output="screen">
<remap from="scan" to="scan" />
</node>
<node name="cartographer_occupancy_grid_node" pkg="cartographer_ros"
type="cartographer_occupancy_grid_node" args="-resolution 0.05" />
</launch>
只需要关注 backpack_2d.urdf和 backpack_2d.lua文件
<robot name="cartographer_backpack_2d">
<material name="orange">
<color rgba="1.0 0.5 0.2 1" />
</material>
<material name="gray">
<color rgba="0.2 0.2 0.2 1" />
</material>
<link name="laser">
<visual>
<origin xyz="0 0 0" />
<geometry>
<cylinder length="0.05" radius="0.03" />
</geometry>
<material name="gray" />
</visual>
</link>
<link name="base_link" />
<joint name="laser_link_joint" type="fixed">
<parent link="base_link" />
<child link="laser" />
<origin rpy="0 0 0" xyz="0.14 0 0.03" />
</joint>
</robot>
不用修改，但是需要注意底盘主机中的cartographer参数是否正确。
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 = false,
use_pose_extrapolator = true,
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.num_accumulated_range_data = 4
return options
不用修改，需要注意底盘主机中 cartographer/configuration_files/backpack_2d.lua参数是否正确。
（1）底盘启动机器人底盘节点，获取/odom和/tf话题。注意/cmd_vel需要remap成/smooth_cmd_vel话题，同时也需要启动速度平滑节点，修改速度平滑节点的launch文件。 <remap from="/cmd_vel" to="/smooth_cmd_vel"></remap>
roslaunch base_controller lp_robot.launch
（2）底盘启动激光雷达节点，获取/scan话题
roslaunch pavo_ros pavo_scan.launch
（3）底盘启动键盘控制节点，调节到合适的速度值
rosrun teleop_twist_keyboard teleop_twist_keyboard.py
（4）底盘启动速度平滑节点，需要修改launch文件的订阅的话题。
roslaunch yocs_velocity_smoother standalone.launch
（5）自己的电脑从机上打开rviz，选择配置好的rviz， cartographer_ros/configuration_files/demo_2d.rviz
rviz
（6）底盘启动建图节点
roslaunch cartographer_ros demo_backpack_2d.launch
（7）机器人运动一段距离，跑遍室内的环境后，结束建图的数据接收，底盘终端运行命令
rosservice call /finish_trajectory 0
（8）保存成pbstream文件，底盘终端运行命令
rosservice call /write_state "{filename: '${HOME}/Downloads/floor_24.pbstream'}"
（9）将pbstream文件转化成pgm文件，底盘终端运行， 完成建图
rosrun cartographer_ros cartographer_pbstream_to_ros_map -map_filestem=/home/lanpu/Downloads/floor_24 -pbstream_filename=/home/lanpu/Downloads/floor_24.pbstream -resolution=0.05
本文中列出一些的配置文件很多都不用修改，只需要将demo_backpack_2d.launch文件中的bag播放节点删掉，注释掉rviz启动节点。本文中列出的配置文件目的是要逐个检查一遍，防止出现实时建图与离线建图参数配置不一致，因为离线建图是在从机中，实时建图是在主机中。
Original: https://blog.csdn.net/qq_41821678/article/details/125140559
Author: 酸梅果茶
Title: Cartographer实时建图（个人定制版）
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