lidar_obstacle_avoidance

A simple tool to split the lidar data into multiple areas, just like multiple ultrasonic sensors

Author: Sunshengjin @MindPointEye [email protected]

---

Why made it

Because the ultrasonic sensor is not so reliable, and in the mobile robot or some area protection tasks, it is necessary to detect and warn the obstacles in a specific range or area, so i made this small tool and used the reliable data of the lidar to be divided into multiple programmable areas to detect obstacles.

How to use it

Recommended system environment: Ubuntu16.04 + ROS Kinetic

• Note:It not rely heavily on a specific system environment, It can also run smoothly on other system versions, Such as Ubuntu14.04 + ROS Indigo.

Step 1

Copy this package into your {ros_workspace}/src

    $ cd catkin_workspace/src
    $ git clone https://github.com/Sunshengjin/lidar_obstacle_avoidance.git
    $ cd ../

Step 2

Compile your ros workspace

    $ catkin_make
    $ rospack profile

Step 3

Please run your lidar driver node Note:Make sure your lidar publish topic is as seem as the topic setting which in the demo.launch.
Then you can run this tool:

    $ roslaunch lidar_obstacle_avoidance demo.launch

Configuration

This tools just subscribe the lidar scan topic ,and it will publish several topic based on the number you set the areas. The configuration file is {ros_workspace}/src/lidar_obstacle_avoidance/launch/demo.launch.

demo.launch

   <arg name="Pi" value="3.1415926"/>
   <node name="loa_node" pkg="lidar_obstacle_avoidance" type="loa_node" output="screen" respawn="true">
      
       <param name="scan_topic" type="string" value="/scan"/>

       <param name="num_of_area" type="int" value="5"/>


       <param name="area_1_min_ang"    type="double" value="-90"/>
       <param name="area_1_max_ang"      type="double" value="-60"/>
       <param name="area_1_max_range"    type="double" value="3"/>
       <param name="area_1_min_range"      type="double" value="1"/>
       <param name="area_1_filter_size"  type="int"    value="3"/>

       <param name="area_2_min_ang"    type="double" value="-50"/>
       <param name="area_2_max_ang"      type="double" value="-20"/>
       <param name="area_2_max_range"    type="double" value="3"/>
       <param name="area_2_min_range"      type="double" value="1"/>
       <param name="area_2_filter_size"  type="int"    value="3"/>


       <param name="area_3_min_ang"    type="double" value="-10"/>
       <param name="area_3_max_ang"      type="double" value="20"/>
       <param name="area_3_max_range"    type="double" value="3"/>
       <param name="area_3_min_range"      type="double" value="1"/>
       <param name="area_3_filter_size"  type="int"    value="3"/>
       
       <param name="area_4_min_ang"    type="double" value="30"/>
       <param name="area_4_max_ang"      type="double" value="50"/>
       <param name="area_4_max_range"    type="double" value="3"/>
       <param name="area_4_min_range"      type="double" value="1"/>
       <param name="area_4_filter_size"  type="int"    value="3"/>

       <param name="area_5_min_ang"    type="double" value="60"/>
       <param name="area_5_max_ang"      type="double" value="90"/>
       <param name="area_5_max_range"    type="double" value="3"/>
       <param name="area_5_min_range"      type="double" value="1"/>
       <param name="area_5_filter_size"  type="int"    value="3"/>
   </node>

   <!--ang to rad :rad =  PI/180 * ang -->
   <!--How to calculat the Yaw set -->
   <!-- Yaw = (max_ang + min_ang)/2 * (PI / 180) -->
   <node pkg="tf" type="static_transform_publisher" name="lidar_to_range1" args="0.0 0.0 0.0 -1.309 0.0 0.0 /laser /range1 40"/>
   <node pkg="tf" type="static_transform_publisher" name="lidar_to_range2" args="0.0 0.0 0.0 -0.611 0.0 0.0 /laser /range2 40"/>
   <node pkg="tf" type="static_transform_publisher" name="lidar_to_range3" args="0.0 0.0 0.0 0.0872 0.0 0.0 /laser /range3 40"/>
   <node pkg="tf" type="static_transform_publisher" name="lidar_to_range4" args="0.0 0.0 0.0 0.698 0.0 0.0 /laser /range4 40"/>
   <node pkg="tf" type="static_transform_publisher" name="lidar_to_range5" args="0.0 0.0 0.0 1.309 0.0 0.0 /laser /range5 40"/>
</launch>

If you want to change the configuration to what you need,just follow the steps below:

Step 1

Make sure your lidar publish topic is as seem as the topic setting which in the demo.launch.

       <param name="scan_topic" type="string" value="/scan"/>

Step 2

Set the number of the defence area.

       <param name="num_of_area" type="int" value="5"/>

Step 3

Set parameters for each area.

example:
       <param name="area_1_min_ang"    type="double" value="-90"/>
       <param name="area_1_max_ang"      type="double" value="-60"/>
       <param name="area_1_max_range"    type="double" value="3"/>
       <param name="area_1_min_range"      type="double" value="1"/>
       <param name="area_1_filter_size"  type="int"    value="3"/>

• min_ang : start angle of the area [ang]

• max_ang : end angle of the area [ang]

• max_range : maximum range value [m]

• min_range : minimum range value [m]

• filter_size : The size of the data filter.If the number of obstacle sampling points is less than the set value,this data will be ignored.

Step 4

Set the transform tree for each area

example:
   <node pkg="tf" type="static_transform_publisher" name="lidar_to_range1" args="0.0 0.0 0.0 -1.309 0.0 0.0 /laser /range1 40"/>

Note:you only need to set the 4th parameter of the args tags,you need to manually calculate the value of this parameter yourself. The calculation formula is {Yaw = (max_ang + min_ang)/2 * (PI / 180)}

Step 5

Now you can run this tools ,and you can subscribe the range topic : /rangeX (X is which of the area range data you want to get).