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Version: ROS 2 Humble

3D Lidar

Three dimensional LiDARs provide a pointcloud of all points detected by several planar scanners at various angles, which is published as a sensor_msgs/PointCloud2 message. It is important to accurately position the LiDAR in the visual descriptiuon of the robot to ensured that the scanned points are accurate with respect to the robot.

Velodyne Lidar​

# Model VLP16
lidar3d:
  - model: velodyne_lidar
    urdf_enabled: true
    launch_enabled: true
    parent: base_link
    xyz: [0.0, 0.0, 0.0]
    rpy: [0.0, 0.0, 0.0]
    ros_parameters:
      velodyne_driver_node:
        frame_id: lidar3d_0_laser
        device_ip: 192.168.131.25
        port: 2368
        model: VLP16
      velodyne_transform_node:
        model: VLP16
        fixed_frame: lidar3d_0_laser
        target_frame: lidar3d_0_laser
# Model 32C
lidar3d:
  - model: velodyne_lidar
    urdf_enabled: true
    launch_enabled: true
    parent: base_link
    xyz: [0.0, 0.0, 0.0]
    rpy: [0.0, 0.0, 0.0]
    ros_parameters:
      velodyne_driver_node:
        frame_id: lidar3d_0_laser
        device_ip: 192.168.131.25
        port: 2368
        model: 32C
      velodyne_transform_node:
        model: 32C
        calibration: "/opt/ros/humble/share/\
          velodyne_pointcloud/params/VeloView-VLP-32C.yaml"
        fixed_frame: lidar3d_0_laser
        target_frame: lidar3d_0_laser

Package and Setup​

The Velodyne LiDARs use the velodyne_driver ROS 2 Package. The driver is open source, maintained by the ROS community, and hosted on GitHub. Unlike other drivers, the visual description of the device is hosted in a separate repository. The description package, along with the simulator, is maintained by Dataspeed and hosted on BitBucket.

For more specifics on the way Clearpath's configuration system launches the velodyne_driver, see the Velodyne launch file and the default parameter file in clearpath_sensors.

Model​

There are several types of Velodyne LiDAR. To switch between these, the model parameter must be set under the both the velodyne_driver_node and the velodyne_transform_node, and the calibration parameter must be set under the velodyne_transform_node.

NameModelCalibration
Puck"VLP16""VLP16db.yaml"
Puck Hi-Res"VLP16""VLP16_hires_db.yaml"
Ultra Puck"32C""VeloView-VLP-32C.yaml"
VLS-128"VLS128""VLS128.yaml"
HDL-32E"32E""32db.yaml"
HDL-64E"64E""64e_utexas.yaml"
HDL-64ES2"64E_S2""64e_s2.1-sztaki.yaml"
HDL-64ES3"64E_S3""64e_s3-xiesc.yaml"

When setting the calibration parameter, prepend the path /opt/ros/humble/share/velodyne_pointcloud/params/ to the calibration file name in the table above.

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