vlp_ws

Velodyne Workspace

Simulation Setup

Add description in defined robot

1. Declared necessary argument and your own robot_gazebo.urdf.xacro

   <xacro:arg name="gpu" default="false"/>
   <xacro:arg name="organize_cloud" default="false"/>
   <xacro:property name="gpu" value="$(arg gpu)" />
   <xacro:property name="organize_cloud" value="$(arg organize_cloud)" />

2. Include the velodyne_description package

   <xacro:include filename="$(find velodyne_description)/urdf/VLP16.urdf.xacro" />

3. Add LiDAR in the robot

   <xacro:VLP-16 parent="base_footprint" name="velodyne" topic="/velodyne_points" organize_cloud="${organize_cloud}" hz="10" samples="440" gpu="${gpu}">
       <origin xyz="0 0 0.1" rpy="0 0 0" />
   </xacro:VLP-16>

• You could refer to more information from veloyne_simulator/velodyne_description/urdf/template.urdf.xacro

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Launch LiDAR driver with simulated LiDAR

• Launch example robot with LiDAR

  ros2 launch velodyne_description example.launch.py

• Launch the LiDAR data process without driver in another terminal

  ros2 launch vlp_cartographer vlp_driver.launch.py is_sim:=True

Sample Robot

• A given turtlebot waffle model with VLP-16 is provided in velodyne_simulator/velodyne_simulator/urdf/sample_robot.urdf.xacro

• Launch the sample robot

  ros2 launch velodyne_description example.launch.py robot:=1

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LiDAR setup

Hardware Setup

• Connect the LiDAR to power.
• Connect the LiDAR to the computer or router using the provided ethernet cable.

Directly Using Computer

• Connect the LiDAR to the computer using the ethernet cable.
• Open the computer settings and navigate to Network > Wired.

• Set the IPv4 configuration to 'manual' and configure the settings as shown in the image below:

Launch the Driver

Pipeline

• Data process as following: raw data -> pointcloud -> laser scan -> slam method

• Velodyne driver: velodyne_driver get the raw data from LiDAR.

• Transform the raw data to pointcloud: velodyne_pointcloud

• Transform the pointcloud to laser scan: velodyne_laserscan

Operating in a single launch file

ros2 launch vlp_cartographer vlp_driver.launch.py

• By the above command, the driver, pointcloud and laserscan will be launched.

Published topics

Topic	Type	Description
/velodyne_packets	velodyne_msgs/VelodyneScan	raw data
/velodyne_points	sensor_msgs/PointCloud2	Point cloud message
/scan	sensor_msgs/LaserScan	laser scan message

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Test with cartographer

• In another terminal, launch the cartographer node:

  ros2 launch vlp_cartographer cartographer_demo.launch.py

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Bringup

• Build the docker image and workspace

  docker compose up --build

• LiDAR driver

  docker exec -it ros2-vlp-ws /home/ros2-essentials/vlp_ws/scripts/lidar-driver-bringup.sh

• After launching the driver, launch the cartographer in another terminal

  docker exec -it ros2-vlp-ws /home/ros2-essentials/vlp_ws/scripts/lidar-slam-bringup.sh

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Reference

• Velodyne_driver with ROS2 Humble
• Cartographer ROS
• Turtlebot3 with Cartographer