How to start multiple Lidar in one file in ros2 environment

asked 2021-08-02 06:12:41 -0500

ylh
76 ●5 ●9 ●10

updated 2021-08-05 04:30:23 -0500

Hello, friends. In ros1,Ｉcan start two lidar in a file,like this: https://github.com/JeongJae0815/Multi... it use the ＜group＞label.It's a ros1 sytle,the launch file write in XML. But in ros2,the launch file wite by python,how to start multiple Lidar in one file in ros2 environment?I'm a beginner to the velodyne_ros2_driver.The official driver is https://github.com/ros-drivers/velody.... I dont know how to start two velodyne in a launch file.I am looking forward to your reply, my friend.

Official launch of a velodyne_16 file:

import os
import yaml

import ament_index_python.packages
import launch
import launch_ros.actions


def generate_launch_description():
    driver_share_dir = ament_index_python.packages.get_package_share_directory('velodyne_driver')
    driver_params_file = os.path.join(driver_share_dir, 'config', 'VLP16-velodyne_driver_node-params.yaml')
    velodyne_driver_node = launch_ros.actions.Node(package='velodyne_driver',
                                                   node_executable='velodyne_driver_node',
                                                   output='both',
                                                   parameters=[driver_params_file])

    convert_share_dir = ament_index_python.packages.get_package_share_directory('velodyne_pointcloud')
    convert_params_file = os.path.join(convert_share_dir, 'config', 'VLP16-velodyne_convert_node-params.yaml')
    with open(convert_params_file, 'r') as f:
        convert_params = yaml.safe_load(f)['velodyne_convert_node']['ros__parameters']
    convert_params['calibration'] = os.path.join(convert_share_dir, 'params', 'VLP16db.yaml')
    velodyne_convert_node = launch_ros.actions.Node(package='velodyne_pointcloud',
                                                    node_executable='velodyne_convert_node',
                                                    output='both',
                                                    parameters=[convert_params])

    laserscan_share_dir = ament_index_python.packages.get_package_share_directory('velodyne_laserscan')
    laserscan_params_file = os.path.join(laserscan_share_dir, 'config', 'default-velodyne_laserscan_node-params.yaml')
    velodyne_laserscan_node = launch_ros.actions.Node(package='velodyne_laserscan',
                                                      node_executable='velodyne_laserscan_node',
                                                      output='both',
                                                      parameters=[laserscan_params_file])


    return launch.LaunchDescription([velodyne_driver_node,
                                     velodyne_convert_node,
                                     velodyne_laserscan_node,

                                     launch.actions.RegisterEventHandler(
                                         event_handler=launch.event_handlers.OnProcessExit(
                                             target_action=velodyne_driver_node,
                                             on_exit=[launch.actions.EmitEvent(
                                                 event=launch.events.Shutdown())],
                                         )),
                                     ])

How do we write with ＜group＞ when multiple are started?friends.Thanks in advance! /_\

Comments

Declaring two Nodes with different names or different namespaces should work. ROS2 also have group launch action, you can refer to turtlebot3 GitHub page to see some examples

Fetullah Atas ( 2021-08-02 16:41:31 -0500 )edit

Here is another example of a group launch from navigation2 https://github.com/ros-planning/navig...

Fetullah Atas ( 2021-08-02 16:43:43 -0500 )edit

My friend, thank you very much for your reply, which is very helpful to me！

ylh ( 2021-08-02 20:44:27 -0500 )edit

You may also need to remap topics so that they don’t publish to same topic

Fetullah Atas ( 2021-08-02 23:45:49 -0500 )edit

Ok, my friend, I'll try it

ylh ( 2021-08-03 00:41:37 -0500 )edit

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answered 2021-08-05 04:28:03 -0500

ylh
76 ●5 ●9 ●10

updated 2021-08-05 19:45:45 -0500

I have solved this problem with the help of friend ,Fetullah Atas ,and this tutorial： https://roboticsbackend.com/ros2-laun... following code：

import os
import yaml

import ament_index_python.packages
from launch import LaunchDescription
from launch_ros.actions import Node

#velodyne_1
def generate_launch_description():
    ld = LaunchDescription()

    driver_share_dir_1 = ament_index_python.packages.get_package_share_directory('velodyne_driver')
    driver_params_file_1 = os.path.join(driver_share_dir_1, 'config', 'vlp_1.yaml')
    velodyne_driver_node_1 = Node(
        package="velodyne_driver",
        executable="velodyne_driver_node",
        name="velodyne_driver_node_1",
        parameters=[driver_params_file_1],
        remappings=[
            ("velodyne_packets", "velodyne_packets_1")
        ]
    )

    convert_share_dir_1 = ament_index_python.packages.get_package_share_directory('velodyne_pointcloud')
    convert_params_file_1 = os.path.join(convert_share_dir_1, 'config', 'VLP16-velodyne_convert_node-params.yaml')
    with open(convert_params_file_1, 'r') as f:
        convert_params_1 = yaml.safe_load(f)['velodyne_convert_node']['ros__parameters']
    convert_params_1['calibration'] = os.path.join(convert_share_dir_1, 'params', 'VLP16db.yaml')
    velodyne_convert_node_1 = Node(
        package="velodyne_pointcloud",
        executable="velodyne_convert_node",
        name="velodyne_convert_node_1",
        parameters=[convert_params_1],
        remappings=[
            ("velodyne_packets", "velodyne_packets_1"),
            ("velodyne_points", "velodyne_points_1")
        ]
    )

    laserscan_share_dir_1 = ament_index_python.packages.get_package_share_directory('velodyne_laserscan')
    laserscan_params_file_1 = os.path.join(laserscan_share_dir_1, 'config', 'default-velodyne_laserscan_node-params.yaml')
    velodyne_laserscan_node_1 = Node(
        package="velodyne_laserscan",
        executable="velodyne_laserscan_node",
        name="velodyne_laserscan_node_1",
        parameters=[laserscan_params_file_1],
        remappings=[
            ("velodyne_points", "velodyne_points_1"),
            ("scan", "scan_1")
        ]
    )

    #velodyne_2
    driver_share_dir_2 = ament_index_python.packages.get_package_share_directory('velodyne_driver')
    driver_params_file_2 = os.path.join(driver_share_dir_2, 'config', 'vlp_1.yaml')
    velodyne_driver_node_2 = Node(
        package="velodyne_driver",
        executable="velodyne_driver_node",
        name="velodyne_driver_node_2",
        parameters=[driver_params_file_2],
        remappings=[
            ("velodyne_packets", "velodyne_packets_2")
        ]
    )

    convert_share_dir_2 = ament_index_python.packages.get_package_share_directory('velodyne_pointcloud')
    convert_params_file_2 = os.path.join(convert_share_dir_2, 'config', 'VLP16-velodyne_convert_node-params.yaml')
    with open(convert_params_file_2, 'r') as f:
        convert_params_2 = yaml.safe_load(f)['velodyne_convert_node']['ros__parameters']
    convert_params_2['calibration'] = os.path.join(convert_share_dir_2, 'params', 'VLP16db.yaml')
    velodyne_convert_node_2 = Node(
        package="velodyne_pointcloud",
        executable="velodyne_convert_node",
        name="velodyne_convert_node_2",
        parameters=[convert_params_2],
        remappings=[
            ("velodyne_packets", "velodyne_packets_2"),
            ("velodyne_points", "velodyne_points_2")
        ]
    )

    laserscan_share_dir_2 = ament_index_python.packages.get_package_share_directory('velodyne_laserscan')
    laserscan_params_file_2 = os.path.join(laserscan_share_dir_2, 'config', 'default-velodyne_laserscan_node-params.yaml')
    velodyne_laserscan_node_2 = Node(
        package="velodyne_laserscan",
        executable="velodyne_laserscan_node",
        name="velodyne_laserscan_node_2",
        parameters=[laserscan_params_file_2],
        remappings=[
            ("velodyne_points", "velodyne_points_2"),
            ("scan", "scan_2")
        ]
    )     

    ld.add_action(velodyne_driver_node_1)
    ld.add_action(velodyne_convert_node_1)
    ld.add_action(velodyne_laserscan_node_1)
    ld.add_action(velodyne_driver_node_2)
    ld.add_action(velodyne_convert_node_2)
    ld.add_action(velodyne_laserscan_node_2)
    return ld

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Comments

The roboticsbackend link seems to be broken

abhishek47 ( 2021-08-05 05:44:58 -0500 )edit

My friend,you can also refer to this link : https://docs.ros.org/en/foxy/Guides/L...

ylh ( 2021-08-07 02:03:38 -0500 )edit

I have done similar modification on the launch file. However, the start log info of ros2 launch showing that the .yaml config actually not being loaded as expected, mine are 2 x VLP 16, but it loaded a 64E model with default port 2368.

ThomasL624 ( 2022-11-08 01:43:48 -0500 )edit

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How to start multiple Lidar in one file in ros2 environment

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