how to increase the rplidar S2 publishing frequency upto 15Hz?

[debanik123]

how to increase the rplidar S2 publishing frequency upto 15Hz? Rplidar current publish frequency is only 10Hz. However the publishing frequency of rplidar A2 is 13 to 15 Hz.

[kbln]

I have the same question! anyone can help please?

[Nikhil619]

Were you able to solve it? If so, Did you change the frequency in the launch file or.... What exactly did you do?

Thanks in advance

[deyouslamtec]

Modify the scan_frequency parameter in the corresponding launch file.

[kosmonauta144]

@deyouslamtec I am also struggling with changing the frequency on ros2 humble and I have included rplidar_s1_launch.py this way

    rplidar_launch = IncludeLaunchDescription(
            PythonLaunchDescriptionSource([str(rplidar_launch_src), '/rplidar_s1_launch.py']),
                launch_arguments={'frame_id': 'laser_link', 'serial_port': '/dev/laser_usb', 'scan_frequency':'15.0'}.items(),
        )

frame_id and serial_port parameters are working, but scan_frequency is not, because after launching I received message like these

[rplidar_node]: current scan mode: DenseBoost, sample rate: 9 Khz, max_distance: 40.0 m, scan frequency:10.0 Hz,

also frequency of the /scan topic is closely about 10 Hz

changing with launch parameter is not working in my case and ros2 launch files.

[EDIT] Even if I added scan_frequency parameter to the rplidar_s1_launch.py as below, in console I am getting proper info but frequency is not changed.

Then I am adding parameter to my own file like below

rplidar_launch = IncludeLaunchDescription(
      PythonLaunchDescriptionSource([str(rplidar_launch_src), '/rplidar_s1_launch.py']),
      launch_arguments={'frame_id': 'laser_link', 'serial_port': '/dev/laser_usb', 'scan_frequency':'15.0'}.items(),
        )

Inside `rplidar_s1_launch.py I added the following lines

    scan_frequency = LaunchConfiguration('scan_frequency', default='10.0')

DeclareLaunchArgument(
            'scan_frequency',
            default_value=scan_frequency,
            description='Specifying scan freqquency for lidar'),

and finally

        Node(
            package='rplidar_ros',
            executable='rplidar_node',
            name='rplidar_node',
            parameters=[{'channel_type':channel_type,
                         'serial_port': serial_port,
                         'serial_baudrate': serial_baudrate,
                         'frame_id': frame_id,
                         'inverted': inverted,
                         'angle_compensate': angle_compensate,
                         'scan_frequency': scan_frequency}],
            output='screen'),

and console gives me this

[rplidar_node]: current scan mode: DenseBoost, sample rate: 9 Khz, max_distance: 40.0 m, scan frequency:15.0 Hz, 

but ros2 topic hz /scan gives me the following average rate: 10.012

[darkhannibal]

I am working with rplidar s1 on ROS1 noetic and after updating launch file in the way @deyouslamtec suggested but still the lidar is not spinning any faster.

While launching there is an info: set lidar scan frequency to 10.0 Hz(600.0 Rpm) I've also checked rostopic hz /scan but it gives me reading of about 10 Hz

[deyouslamtec]

I tested under Ubuntu20.04 ROS noetic. rplidar S1, S2, and S3 can adjust the publishing frequency by modifying scan_frequency in the launch file.

[darkhannibal]

This is content of modified launch I am using:

<launch>
  <node name="rplidarNode"          pkg="rplidar_ros"  type="rplidarNode" output="screen">
    <param name="serial_port"         type="string" value="/dev/ttyUSB0"/>  
    <param name="serial_baudrate"     type="int"    value="256000"/>
    <param name="frame_id"            type="string" value="laser"/>
    <param name="inverted"            type="bool"   value="false"/>
    <param name="angle_compensate"    type="bool"   value="true"/>
    <param name="scan_frequncy"      type="double" value="15.0"/>
  </node>
</launch>

after launching it I get So the ros parameter is being set, but does not affect the lidar

[deyouslamtec]

@darkhannibal 'scan_frequency' not 'scan_frequncy'

[darkhannibal]

@deyouslamtec Thanks man, now it works like a charm. I have not noticed that typo :/

[kosmonauta144]

@deyouslamtec does the same work on ROS2? Cause I tried to add this parameter to launch with default value of 15.0 and it does not change anything :crying_cat_face:

def generate_launch_description():
    channel_type = LaunchConfiguration('channel_type', default='serial')
    serial_port = LaunchConfiguration('serial_port', default='/dev/ttyUSB0')
    serial_baudrate = LaunchConfiguration('serial_baudrate', default='256000') 
    frame_id = LaunchConfiguration('frame_id', default='laser')
    inverted = LaunchConfiguration('inverted', default='false')
    angle_compensate = LaunchConfiguration('angle_compensate', default='true')
    scan_frequency = LaunchConfiguration('scan_frequency', default='15.0')

    return LaunchDescription([
        DeclareLaunchArgument(
            'channel_type',
            default_value=channel_type,
            description='Specifying channel type of lidar'),

        DeclareLaunchArgument(
            'serial_port',
            default_value=serial_port,
            description='Specifying usb port to connected lidar'),

        DeclareLaunchArgument(
            'serial_baudrate',
            default_value=serial_baudrate,
            description='Specifying usb port baudrate to connected lidar'),

        DeclareLaunchArgument(
            'frame_id',
            default_value=frame_id,
            description='Specifying frame_id of lidar'),

        DeclareLaunchArgument(
            'inverted',
            default_value=inverted,
            description='Specifying whether or not to invert scan data'),

        DeclareLaunchArgument(
            'angle_compensate',
            default_value=angle_compensate,
            description='Specifying whether or not to enable angle_compensate of scan data'),

        DeclareLaunchArgument(
            'scan_frequency',
            default_value=scan_frequency,
            description='Specifying whether or not to enable angle_compensate of scan data'),

        Node(
            package='rplidar_ros',
            executable='rplidar_node',
            name='rplidar_node',
            parameters=[{'channel_type':channel_type,
                         'serial_port': serial_port,
                         'serial_baudrate': serial_baudrate,
                         'frame_id': frame_id,
                         'inverted': inverted,
                         'angle_compensate': angle_compensate,
                         'scan_frequency': scan_frequency}],
            output='screen'),
    ])

Parameters also do not work to increase the frequency

[deyouslamtec]

@kosmonauta144 It doesn't work properly on ROS2 yet, wait for me to adjust the code

[deyouslamtec]

@kosmonauta144 scan_frequcund can work on ROS2, please update the ros2 branch

[kosmonauta144]

thank you very much, it works with parameter from launch file :smile: