Lesson 10: Navigation-Create map based on the laser

Construction of the map is the basis of SLAM, positioning and path planning are based on a certain map to achieve, this section we will be based on the laser radar, using gmapping and hector slam two packages to build the map

1.Lidar

Lidar has a very high measurement accuracy characteristics, is a very good choice of distance measurement, but at the same time he also has high power consumption, high cost shortcomings, the current widespread use of 2D laser radar, intelligent measurement of a plane around the distance, and The cost of 3D laser radar is high and can not be widely promoted at present. 2D laser radar can only measure a plane problem, but also affect the use of the scene, if used as navigation, only suitable for some relatively simple rules in the environment.

In the Diego robot, we use the Flash go F4 radar from EAI, which features the following:

• 360 degree omni-directional scanning, 10 Hz adaptive scanning frequency, 4500 laser strokes per second
• Not less than 8 m range of ranging, measuring the resolution of 1% of the range
• Low noise and long life
Class 1 laser safety standard

F4 using USB interface and the host connection, at the same time with power and data transmission function, so the installation is still very convenient, only need to plug in the host’s USB interface

1.1. The installation of the laser radar ROS driver package

Execute the following command

cd ~/catkin_ws/src
git clone https://github.com/EAIBOT/flashgo.git
cd ..
catkin_make

After the completion of the implementation of the src directory to add a flashgo directory, is the F4 ROS package

 

 

 

 

 

 

 

 

 

1.2. Modify the serial number in the configuration file

F4 USB and motherboard connection, and raspberry connection, the system will appear in a serial port, because Arduino UNO is also connected through the USB serial communication, so there will be two serial devices in the system, the configuration must be clearly distinguish The serial number of the two devices


As shown above ttyACM0, and ttyACM1 is the corresponding serial port number, in the diego1 # ttyACM1 corresponds to arduino, ttyACM0 corresponding F4 laser radar, we need to modify the corresponding parameters, first modify the Ardunio configuration file, open the config directory my_arduino_params.yaml

 

 

 

 

 

Modify the arduino_bridge connection to the serial port for ttyACM1

 

 

 

 

 

 

Modify the F4 configuration file, open the flashar / launch directory under the lidar.launch file

 

 

 

 

 

Modify the F4 connection to the serial port ttyACM0

 

 

 

 

 

 

2.Use hector slam to build a map

2.1Install hector slam

sudo apt-get install ros-kinetic-hector-slam

2.2Write the hector slam to start the launch file

The following code is written hector start launch the file, here need to pay attention to the point of the EAI Flash lidar using the left hand coordinate system, and ROS use the right hand coordinate system, so the need to prepare a file in the static tf type base_frame_2_laser coordinate conversion.

<?xml version="1.0"?>

<launch>
  <arg name="tf_map_scanmatch_transform_frame_name" default="/scanmatcher_frame"/>
  <arg name="pub_map_odom_transform" value="true"/> 
  <arg name="map_frame" value="map"/> 
  <arg name="base_frame" value="base_link"/> 
  <arg name="odom_frame" value="base_link"/>
  <arg name="scan_subscriber_queue_size" default="5"/>
  <arg name="scan_topic" default="scan"/>
  <arg name="map_size" default="2048"/>

  <master auto="start"/>

  <include file="$(find flashgo)/launch/lidar.launch" />

  <node name="arduino" pkg="ros_arduino_python" type="arduino_node.py" output="screen">
      <rosparam file="$(find ros_arduino_python)/config/my_arduino_params.yaml" command="load" />
  </node> 

  <node pkg="tf" type="static_transform_publisher" name="base_frame_2_laser" args="0 0 0 0 0 0 /$(arg base_frame) /laser 100"/>  
  <node pkg="tf" type="static_transform_publisher" name="map_2_odom" args="0.0 0.0 0.0 0 0 0.0 /odom /$(arg base_frame) 10"/>


  <node pkg="hector_mapping" type="hector_mapping" name="hector_mapping" output="screen">   
  <!-- Frame names -->
  <param name="map_frame" value="$(arg map_frame)" />
  <param name="base_frame" value="$(arg base_frame)" />
  <param name="odom_frame" value="$(arg base_frame)" />   
   <!-- Tf use -->
  <param name="use_tf_scan_transformation" value="true"/>
  <param name="use_tf_pose_start_estimate" value="false"/>
  <param name="pub_map_odom_transform" value="$(arg pub_map_odom_transform)"/> 
  <!-- Map size / start point -->
  <param name="map_resolution" value="0.050"/>
  <param name="map_size" value="$(arg map_size)"/>
  <param name="map_start_x" value="0.5"/>
  <param name="map_start_y" value="0.5" />
  <param name="map_multi_res_levels" value="2" />
  <!-- Map update parameters -->
  <param name="update_factor_free" value="0.4"/>
  <param name="update_factor_occupied" value="0.7" />   
  <param name="map_update_distance_thresh" value="0.2"/>
  <param name="map_update_angle_thresh" value="0.9" />
  <param name="laser_z_min_value" value = "-1.0" />
  <param name="laser_z_max_value" value = "1.0" />  
  <!-- Advertising config -->
  <param name="advertise_map_service" value="true"/>
  <param name="scan_subscriber_queue_size" value="$(arg scan_subscriber_queue_size)"/>
  <param name="scan_topic" value="$(arg scan_topic)"/>
  <param name="tf_map_scanmatch_transform_frame_name" value="$(arg tf_map_scanmatch_transform_frame_name)" />
  </node>

  <include file="$(find hector_geotiff)/launch/geotiff_mapper.launch"/> 

</launch>

2.3 start hector slam

Now you can execute the following code to start the lidar

roslaunch diego_nav diego_run_hector_flashgo.launch

At this time we can control through the keyboard diego # in the room movement, start rviz can draw the corresponding map, in different terminals in the implementation of the following order
rosrun teleop_twist_keyboard teleop_twist_keyboard.py
rosrun rviz rviz

3.Use gmapping to map

3.1Install the ros navigation package

sudo apt-get install ros-kinetic-navigation

gmapping,acml,move_base will be installed after the implementation

3.2Write the gmapping package to launch the launch file

<launch>
<master auto="start"/>

<include file="$(find flashgo)/launch/lidar.launch" />

<node name="arduino" pkg="ros_arduino_python" type="arduino_node.py" output="screen">
<rosparam file="$(find ros_arduino_python)/config/my_arduino_params.yaml" command="load" />
</node>

<node pkg="tf" type="static_transform_publisher" name="base_frame_2_laser_link" args="0.0 0.0 0.2 3.14 3.14 0 /base_link /laser 40"/>

<!-- gmapping node -->
<node pkg="gmapping" type="slam_gmapping" name="slam_gmapping">
<param name="base_frame" value="base_link"/>
<param name="odom_frame" value="odom"/>
<param name="maxUrange" value="4.0"/>
<param name="maxRange" value="5.0"/>
<param name="sigma" value="0.05"/>
<param name="kernelSize" value="3"/>
<param name="lstep" value="0.05"/>
<param name="astep" value="0.05"/>
<param name="iterations" value="5"/>
<param name="lsigma" value="0.075"/>
<param name="ogain" value="3.0"/>
<param name="lskip" value="0"/>
<param name="minimumScore" value="30"/>
<param name="srr" value="0.01"/>
<param name="srt" value="0.02"/>
<param name="str" value="0.01"/>
<param name="stt" value="0.02"/>
<param name="linearUpdate" value="0.05"/>
<param name="angularUpdate" value="0.0436"/>
<param name="temporalUpdate" value="-1.0"/>
<param name="resampleThreshold" value="0.5"/>
<param name="particles" value="8"/>
<!--
<param name="xmin" value="-50.0"/>
<param name="ymin" value="-50.0"/>
<param name="xmax" value="50.0"/>
<param name="ymax" value="50.0"/>
make the starting size small for the benefit of the Android client's memory...
-->
<param name="xmin" value="-1.0"/>
<param name="ymin" value="-1.0"/>
<param name="xmax" value="1.0"/>
<param name="ymax" value="1.0"/>

<param name="delta" value="0.05"/>
<param name="llsamplerange" value="0.01"/>
<param name="llsamplestep" value="0.01"/>
<param name="lasamplerange" value="0.005"/>
<param name="lasamplestep" value="0.005"/>
</node>
</launch>

3.3 start gmapping

Now you can execute the following code to start the lidar

roslaunch diego_nav diego_run_gmapping_flashgo.launch

At this time we can control through the keyboard diego # in the room movement, start rviz can draw the corresponding map, in different terminals in the implementation of the following order
rosrun teleop_twist_keyboard teleop_twist_keyboard.py
rosrun rviz rviz

4.Generate map files

Whether you use hector or gmapping to create a map dynamically, we can generate a map file by command

4.1.Create the maps folder

The map file needs to give it permission to 777, allowing map_server to generate a map file in this folder

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.2.Generate map files

Open the terminal cd into the maps directory and execute the map generation command

cd ~/catkin_ws/src/diego_nav/maps/

rosrun map_server map_saver -f f4_gmapping

 

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