先驱动雷达
$roslaunch rslidar_pointcloud rs_lidar_16.launch
再运行pointcloud_to_laserscan节点将三维数据转化成二维
$ roslaunch pointcloud_to_laserscan point_to_scan.launch
最后运行cartographer
~/cartographer_ws$ source install_isolated/setup.bash

$roslaunch cartographer_ros cartographer_demo_rslidar.launch

cartographer相关配置：

launch文件：

  <param name="/use_sim_time" value="true" />

  <node name="cartographer_node" pkg="cartographer_ros"
      type="cartographer_node" args="
          -configuration_directory $(find cartographer_ros)/configuration_files
          -configuration_basename rslidar.lua"
      output="screen">
    <remap from="scan" to="scan" />     ！！注意雷达数据经过转换后这里是scan
  </node>

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

.lua文件：

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

options = {
  map_builder = MAP_BUILDER,
  trajectory_builder = TRAJECTORY_BUILDER,
  map_frame = "map",
  tracking_frame = "rslidar",			！！注意这里是雷达的坐标系
  published_frame = "rslidar",
  odom_frame = "odom",
  provide_odom_frame = true,
  publish_frame_projected_to_2d = 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.submaps.num_range_data = 35
TRAJECTORY_BUILDER_2D.min_range = 0.3
TRAJECTORY_BUILDER_2D.max_range = 8.
TRAJECTORY_BUILDER_2D.missing_data_ray_length = 1.
TRAJECTORY_BUILDER_2D.use_imu_data = false
TRAJECTORY_BUILDER_2D.use_online_correlative_scan_matching = true
TRAJECTORY_BUILDER_2D.real_time_correlative_scan_matcher.linear_search_window = 0.1
TRAJECTORY_BUILDER_2D.real_time_correlative_scan_matcher.translation_delta_cost_weight = 10.
TRAJECTORY_BUILDER_2D.real_time_correlative_scan_matcher.rotation_delta_cost_weight = 1e-1

POSE_GRAPH.optimization_problem.huber_scale = 1e2
POSE_GRAPH.optimize_every_n_nodes = 35
POSE_GRAPH.constraint_builder.min_score = 0.65

return options

总结：cartographer算法进行3D建图必须要IMU数据，2D可以不使用IMU，因此需要将三维数据先转换成二维，即pointcloud2scan。不然一直会提示找不到map坐标系，实际上是因为算法找不到traking frame 导致无法提供它与map之间的transform关系，生成不了map坐标系。
雷达自身带有rslidar frame，不需要再另外构建tf关系，可以直接将traking frame设置为rslidar，完成手持雷达建图。