Unlocking advanced mapping capabilities, LIMO offers a sophisticated suite of tools for precise environment visualization. Leveraging state-of-the-art technologies like the YDLIDAR T-mini Pro LiDAR and versatile SLAM algorithms such as Gmapping and Cartographer, LIMO ensures accurate mapping in diverse settings. With the autonomous exploration prowess of the RRT algorithm, LIMO navigates and maps unknown terrains autonomously, setting new standards in robotics mapping efficiency and precision.

Table of Contents

YDLIDAR T-mini Pro lidar is a 360° 2D lidar (hereinafter referred to as T-mini Pro) developed by Shenzhen EAI Technology Co., Ltd. This product is based on the pulse ToF ranging principle, and is equipped with related optical, electrical, and algorithm designs to achieve high-frequency and high-precision distance measurement. At the same time, the mechanical structure rotates 360 degrees to continuously obtain angle information, thereby achieving 360-degree scanning ranging, output the point cloud data of the scanning environment.

Items Minimum Default Maximum Unit Remarks
Ranging frequency / 4000 / Hz 4000 ranging times per second
Scanning frequency 6 6 12 Hz PWM signal needs to be connected, and the recommended frequency is 6Hz.
Ranging range 0.02 / 12 m Indoor environment, and objects with 80% reflectivity
Scanning angle / 0-360 / Deg /
Ranging accuracy / 20 / mm When 0.05m <ranging≤12m
Pitch angle 0 0.75 1.5 Deg /
Angle resolution 0.54 Deg

Here's how to use it:

  1. Launch a new terminal and enter the command:

    roslaunch limo_bringup limo_start.launch pub_odom_tf:=false

  2. After launching successfully, the terminal will output the following log information, as shown in the figure:

    https://github.com/agilexrobotics/limo_pro_doc/raw/master/LIMO_image/leida.png

  3. Then launch a new terminal and enter the command in the terminal:

    roslaunch limo_bringup lidar_rviz.launch

  4. After the rviz visualization software runs successfully, the green data displayed is the laser data scanned by LiDAR.

    https://github.com/agilexrobotics/limo_pro_doc/raw/master/LIMO_image/lidar.png

  5. At this time, set the remote control/App to remote control mode and the remote control car will move. The laser data will also change accordingly.

GMAPPING mapping

1. Introduction of gmapping algorithm

Gmapping is a widely adopted open-source SLAM algorithm that operates within the filtering SLAM framework. It effectively uses wheel odometry data and does not heavily rely on high-frequency laser LiDAR scans. When constructing a map of a smaller environment, Gmapping requires minimal computational resources while maintaining high accuracy. Here the ROS encapsulated GMapping package is used to achieve the mapping for Limo.

2. Operation of gmapping mapping

<aside> 💡 Note: Before running the command, please make sure that the programs in other terminals have been terminated. The termination command is: Ctrl+c.

</aside>

<aside> 💡 Note: The speed of limo should be slow in the process of mapping. If the speed is too fast, the effect of mapping will be affected.

</aside>

  1. Launch a new terminal and enter the command:

    roslaunch limo_bringup limo_start.launch pub_odom_tf:=false

  2. Then launch the gmapping mapping algorithm. Open another new terminal, and enter the command:

    roslaunch limo_bringup limo_gmapping.launch

  3. After launching successfully, the rviz visualization tool will start up. The interface is shown in the figure.

    https://github.com/agilexrobotics/limo_pro_doc/raw/master/LIMO_image/gmapping.png

  4. At this time, the handle can be set to remote control mode and control limo mapping.