Velodyne ROS Tools

Overview

The repository provides the velodyne_ros_tools ROS package, which wrapped official velodyne ROS driver for running VLP-16 sensor manufactured by Velodyne LiDAR.

There are three main functionalities (in simple ROS launch files) that is supported in this package:

• VLP16_points.launch: Namespace configuration of multiple VLP-16 LiDARs by its arguments
• VLP16_record.launch: Recording LiDAR packets in rosbag, which significantly reduces the saved file size
• VLP16_from_rosbag.launch: Playback command with visualization of rosbag msgs after recording LiDAR packets

Installation

Prerequisite

This package is a simple wrapper for the official velodyne_pointcloud package. Therefore, you should ensure the installation of the package first.

To install ROS driver, use the following command:

sudo apt install ros-noetic-velodyne-pointcloud

If you need, see more details in Getting Started with the Velodyne VLP 16 pages.

Build package

After the prerequisite configuration, use the following commands to download and compile the package.

cd ~/catkin_ws/src   # navigate to your workspace
git clone https://github.com/Ikhyeon-Cho/velodyne_ros_tools.git
cd ..
catkin build velodyne_ros_tools    # or catkin_make

Getting Started

1. Run the device

To start running Velodyne VLP-16 LiDAR, you should connect to the device first. After, use the command below:

roslaunch velodyne_ros_tools VLP16_points.launch

To launch with rviz for data stream visualization, use the command below:

roslaunch velodyne_ros_tools test_VLP16_points.launch

You can give several command-line arguments to the launch files.

• frame_id (string, default: velodyne)
  The frame id of the LiDAR sensor. This argument is especially useful when you utilize multiple LiDARs. The argument frame_id automatically sets namespace in the nodelets and topics by its value.

• device_ip (default: 192.168.1.201)
  The ip address of the Velodyne LiDAR.

• port (default: 2368)
  The port number of the Velodyne LiDAR.

Here is an example command using launch argument options:

# You can use multiple Velodyne LiDARs like this:
# Publish 'velodyne_front/points' from velodyne_front LiDAR
# Publish 'velodyne_back/points' from velodyne_back LiDAR

roslaunch velodyne_ros_tools VLP16_points.launch frame_id:=velodyne_front
roslaunch velodyne_ros_tools VLP16_points.launch frame_id:=velodyne_back 

2. Record data

To record the pointcloud streams, use the command below. Before starting the records, make sure that the device is running.

roslaunch velodyne_ros_tools VLP16_record.launch    # Default: 'velodyne_lidar.bag' is saved to {$HOME}/Downloads/ 

The command will save the rosbag file to $HOME/Downloads folder. By default, the name of rosbag is velodyne_lidar.bag.

For assigning a specific name to the rosbag, use the command with bag_file:= launch argument like below:

roslaunch velodyne_ros_tools VLP16_record.launch bag_file:=example.bag    # now, 'example.bag' is saved

When you specify the project_dir:= argument, the rosbag is saved in {$HOME}/Downloads/{project-dir-value} like below:

roslaunch velodyne_ros_tools VLP16_record.launch project_dir:=outdoor_navigation

# now, bag file is saved to {$HOME}/Downloads/outdoor_navigation/

If you use multiple LiDARS and aim to record each data streams, then you can specify the frame_id arguments like below:

# For recording with the frame id: velodyne_front 
roslaunch velodyne_ros_tools VLP16_record.launch frame_id:=velodyne_front

3. Data playback

To playback the recorded rosbag, use the following command. By default, we assume that rosbag files are located at {$HOME}/Downloads folder.

# Playback velodyne_lidar.bag
roslaunch velodyne_ros_tools VLP16_from_rosbag.launch bag_file:=velodyne_lidar.bag   

You can give several command-line arguments to the launch files.

• bag_file (string, default: velodyne_lidar.bag)
  The bagfile name for playing.

• project_dir (string, default: "")
  The project directory of bagfile in ~/Downloads/.

• playback_speed (double, default: 1.0)
  The playback speed of bagfile.

• start_time (double, default: 0.0)
  The start time of bagfile playback.