利用Robosense 16線雷達跑cartographer 2D

首先，根據不同的雷達，瞭解雷達發佈的點雲消息。（IMU也是一樣，瞭解IMU發佈的點雲topic）。

本文使用的是Robosense 16線激光雷達，暫時未使用IMU（建議6軸，再加上GPS定位精度會高很多）發佈PointCloud2類型的消息默認的topic爲rslidar_points。

主要步驟分爲：配置URDF文件 —》配置.lua文件—》配置launch文件

上述三個文件分別在cartographer的configura_files、urdf、launch文件夾下。

配置URDF文件

意義：爲方便後面發佈tf轉換，主要內容爲imu、laser、robot的相對位置關係。

<robot name="my_robot">
  <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="imu">
    <visual>
      <origin xyz="0.0 0.0 0.0" />
      <geometry>
        <box size="0.06 0.04 0.02" />
      </geometry>
      <material name="orange" />
    </visual>
  </link>

  <link name="laser">
    <visual>
      <origin xyz="0.0 0.0 0.0" />
      <geometry>
        <cylinder length="0.07" radius="0.05" />
      </geometry>
      <material name="gray" />
    </visual>
  </link>

  <link name="base_link" />

  <joint name="imu2base" type="fixed">
    <parent link="base_link" />
    <child link="imu" />
    <origin xyz="0 0 0" rpy="0 0 0" />
  </joint>

  <joint name="laser2base" type="fixed">
    <parent link="base_link" />
    <child link="laser" />
    <origin xyz="0. 0.1 0." rpy="0. 0. 0." />
  </joint>
  
</robot>

大概意思很簡單，定義了三個構件link以及兩個關節joint，關節處xyz爲相對位移，rpy爲相對旋轉，如果不明白需要自己去學習ros的urdf相關知識。

配置.lua文件

.lua文件的參數會在運行時加載到相關變量處，本處使用2D，而且沒有其餘傳感器，如果需要3d或者其他傳感器，根據需求修改。改的也很少。可以查看官方文檔：

https://google-cartographer-ros.readthedocs.io/en/latest/configuration.html

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

options = {
  map_builder = MAP_BUILDER,
  trajectory_builder = TRAJECTORY_BUILDER,
  map_frame = "map",  #這個是地圖座標系名稱
  tracking_frame = "imu",#設置爲IMU的座標系
  published_frame = "base_link",#設置爲機器人座標系
  odom_frame = "odom",#里程計座標系名稱
  provide_odom_frame = true,
  publish_frame_projected_to_2d = false,
  use_odometry = false,#是否使用編碼器提供odom
  use_nav_sat = false,#是否使用gps
  use_landmarks = false,#是否使用路標
  num_laser_scans = 0,
  num_multi_echo_laser_scans = 0,
  num_subdivisions_per_laser_scan = 1,
  num_point_clouds = 1,
  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.,
}

TRAJECTORY_BUILDER_3D.num_accumulated_range_data = 1

MAP_BUILDER.use_trajectory_builder_3d = true
MAP_BUILDER.num_background_threads = 7
POSE_GRAPH.optimization_problem.huber_scale = 5e2
POSE_GRAPH.optimize_every_n_nodes = 320
POSE_GRAPH.constraint_builder.sampling_ratio = 0.03
POSE_GRAPH.optimization_problem.ceres_solver_options.max_num_iterations = 10
POSE_GRAPH.constraint_builder.min_score = 0.62
POSE_GRAPH.constraint_builder.global_localization_min_score = 0.66

return options

配置launch文件

<launch>
  <param name="/use_sim_time" value="true" />
  
  <param name="robot_description"
    textfile="$(find cartographer_ros)/urdf/my_demo.urdf" />
  <node name="robot_state_publisher" pkg="robot_state_publisher" 
       type="robot_state_publisher"/>

  <node name="rviz" pkg="rviz" type="rviz" required="true"
      args="-d $(find cartographer_ros)/configuration_files/demo_3d.rviz" />

  <node name="cartographer_offline_node" pkg="cartographer_ros"
      type="cartographer_offline_node" args="
          -configuration_directory $(find cartographer_ros)/configuration_files
          -configuration_basenames my_demo.lua
          -urdf_filenames $(find cartographer_ros)/urdf/my_demo.urdf
          -bag_filenames $(arg bag_filenames)"
      output="screen">
    <remap from="points2" to="/rslidar_points" />
    <remap from="imu" to="/imu_raw" />
  </node>

  <node name="cartographer_occupancy_grid_node" pkg="cartographer_ros"
      type="cartographer_occupancy_grid_node" args="-resolution 0.05" />
</launch>

這裏是跑離線bag包的lua，我跑在線，但是機器人沒測試成功。第四段不同之處如下：

 <node name="cartographer_node" pkg="cartographer_ros"
      type="cartographer_offline_node" args="
          -configuration_directory $(find cartographer_ros)/configuration_files
          -configuration_basenames my_demo.lua"
      output="screen">
    <remap from="points2" to="/rslidar_points" />
  </node>

後面還沒測試，等待更新。

參考：

基於Cartographer的3D SLAM（Lidar+IMU）_W_Tortoise的博客-CSDN博客_cartographer3d 定位  https://blog.csdn.net/learning_tortosie/article/details/105158858?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.nonecase&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.nonecase

cartographer 3D運行錄製rosbag包 - 達達MFZ - 博客園  https://www.cnblogs.com/mafuqiang/p/10885458.html