ROS无里程计，单一激光雷达gmapping建图保存

ROS使用gmapping建图，需要激光雷达和里程计，在只有激光雷达的时候，可以使用Laser scan tools for ROS通过激光雷达连续扫描数据推算出里程数据，实现无里程计的激光雷达建图

确保功能包已安装

$ sudo apt-get install ros-melodic-gmapping

安装laser_scan_tools

$ git clone https://github.com/ccny-ros-pkg/scan_tools.git

将laser_scan_matcher功能包文件夹移至ROS项目空间文件夹 /src，并且将雷达功能包也放到同位置，然后进行编译

$ cd ydlidar_ws/src #进入存放的项目空间文件夹
$ catkin_make

进入src/laser_scan_matcher/demo，修改demo_gmapping.launch如下

<!-- 
Example launch file: uses laser_scan_matcher together with
slam_gmapping 
-->

<launch>

  #### set up data playback from bag #############################

  <param name="/use_sim_time" value="flase"/><!-- 因为Gmapping 的simulation 时间是True, 改为false  网上查到的 -->

  #### rplidar_X2L ################################################
  <!--激光雷达的启动文件-->
   <node name="ydlidar_lidar_publisher"  pkg="ydlidar_ros_driver"  type="ydlidar_ros_driver_node" output="screen" respawn="false" >
    <!-- string property -->
    <param name="port"         type="string" value="/dev/ydlidar"/>  
    <param name="frame_id"     type="string" value="laser"/>
    <param name="ignore_array"     type="string" value=""/>

    <!-- int property -->
    <param name="baudrate"         type="int" value="115200"/>  
    <!-- 0:TYPE_TOF, 1:TYPE_TRIANGLE, 2:TYPE_TOF_NET -->
    <param name="lidar_type"       type="int" value="1"/>  
    <!-- 0:YDLIDAR_TYPE_SERIAL, 1:YDLIDAR_TYPE_TCP -->
    <param name="device_type"         type="int" value="0"/>  
    <param name="sample_rate"         type="int" value="3"/>  
    <param name="abnormal_check_count"         type="int" value="4"/>  

    <!-- bool property -->
    <param name="resolution_fixed"    type="bool"   value="true"/>
    <param name="auto_reconnect"    type="bool"   value="true"/>
    <param name="reversion"    type="bool"   value="false"/>
    <param name="inverted"    type="bool"   value="true"/>
    <param name="isSingleChannel"    type="bool"   value="true"/>
    <param name="intensity"    type="bool"   value="false"/>
    <param name="support_motor_dtr"    type="bool"   value="true"/>
    <param name="invalid_range_is_inf"    type="bool"   value="false"/>
    <param name="point_cloud_preservative"    type="bool"   value="false"/>

    <!-- float property -->
    <param name="angle_min"    type="double" value="-180" />
    <param name="angle_max"    type="double" value="180" />
    <param name="range_min"    type="double" value="0.1" />
    <param name="range_max"    type="double" value="12.0" />
    <!-- frequency is invalid, External PWM control speed -->
    <param name="frequency"    type="double" value="10.0"/>
  </node>


  #### publish an example base_link -> laser transform ###########

  <node pkg="tf" type="static_transform_publisher" name="base_link_to_laser" 
    args="0.0 0.0 0.0 0.0 0.0 0.0 /base_link /laser 40" />

  #### start rviz ################################################

  <node pkg="rviz" type="rviz" name="rviz" 
    args="-d $(find laser_scan_matcher)/demo/demo_gmapping.rviz"/>

  #### start the laser scan_matcher ##############################

  <node pkg="laser_scan_matcher" type="laser_scan_matcher_node" 
    name="laser_scan_matcher_node" output="screen">

    <param name="fixed_frame" value = "odom"/>
    <param name="max_iterations" value="10"/>

    <param name="base_frame" value = "base_link"/>
    <param name="use_odom" value="false"/>
    <param name="publy_pose" value = "true"/>
    <param name="publy_tf" value="true"/>


  </node>

  #### start gmapping ############################################
<!--前三个param必须设置修改，要不然tf_tree不完整-->
  <node pkg="gmapping" type="slam_gmapping" name="slam_gmapping" output="screen">
    <param name="base_frame" value="/base_link"/> <!--***机器人的坐标系-->
    <param name="odom_frame" value="/odom" /> <!--***世界坐标系-->
    <param name="map_frame" value="/map" /> <!--***地图坐标系-->

    <param name="map_udpate_interval" value="1.0"/>
    <param name="maxUrange" value="5.0"/>
    <param name="sigma" value="0.1"/>
    <param name="kernelSize" value="1"/>
    <param name="lstep" value="0.15"/>
    <param name="astep" value="0.15"/>
    <param name="iterations" value="1"/>
    <param name="lsigma" value="0.1"/>
    <param name="ogain" value="3.0"/>
    <param name="lskip" value="1"/>
    <param name="srr" value="0.1"/>
    <param name="srt" value="0.2"/>
    <param name="str" value="0.1"/>
    <param name="stt" value="0.2"/>
    <param name="linearUpdate" value="1.0"/>
    <param name="angularUpdate" value="0.5"/>
    <param name="temporalUpdate" value="0.4"/>
    <param name="resampleThreshold" value="0.5"/>
    <param name="particles" value="10"/>
    <param name="xmin" value="-5.0"/>
    <param name="ymin" value="-5.0"/>
    <param name="xmax" value="5.0"/>
    <param name="ymax" value="5.0"/>
    <param name="delta" value="0.02"/>
    <param name="llsamplerange" value="0.01"/>
    <param name="llsamplestep" value="0.05"/>
    <param name="lasamplerange" value="0.05"/>
    <param name="lasamplestep" value="0.05"/>
  </node>

</launch>

如果是其他型号的雷达，可以根据雷达驱动文档，在上述<node name=”ydlidar_lidar_publisher”…>节点找到对应参数进行修改。

在项目空间目录下，启动gmapping demo

roslaunch  laser_scan_matcher demo_gmapping.launch

rviz成功显示扫描出来的空间后，如果需要保存地图，安装map_server功能包

$ sudo apt-get install ros-melodic-map-server

在rviz显示扫描的图像差不多后，另外打开一个控制台

$ rosrun map_server map_saver -f ydlidar_ws/map

其中ydlidar_ws/map，ydlidar_ws为文件路径，map为文件名，最终可以在文件夹中找到map.pgm和map.yaml两个地图文件