说明

本文主要介绍ROS多机系统中如何使用多个VLP16，比如A上配备了一个VLP16，B上配备了一个VLP16。因为已经组成多机，所以简单运行自带的VLP可能出现问题。最终修改launch文件，已解决该问题。

修改launch文件

本文修改的是VLP16_points.launch，源文件内容如下：

<!-- -*- mode: XML -*- -->
<!-- run velodyne_pointcloud/TransformNodelet in a nodelet manager for a VLP-16 -->

<launch>

  <!-- declare arguments with default values -->
  <arg name="calibration" default="$(find velodyne_pointcloud)/params/VLP16db.yaml"/>
  <arg name="device_ip" default="192.168.8.201" />
  <arg name="frame_id" default="velodyne" />
  <arg name="manager" default="$(arg frame_id)_nodelet_manager" />
  <arg name="max_range" default="130.0" />
  <arg name="min_range" default="0.4" />
  <arg name="pcap" default="" />
  <arg name="port" default="2368" />
  <arg name="read_fast" default="false" />
  <arg name="read_once" default="false" />
  <arg name="repeat_delay" default="0.0" />
  <arg name="rpm" default="600" />
  <arg name="gps_time" default="false" />
  <arg name="cut_angle" default="-0.01" />
  <arg name="timestamp_first_packet" default="false" />
  <arg name="laserscan_ring" default="-1" />
  <arg name="laserscan_resolution" default="0.007" />
  <arg name="organize_cloud" default="false" />

  <!-- start nodelet manager and driver nodelets -->
  <include file="$(find velodyne_driver)/launch/nodelet_manager.launch">
    <arg name="device_ip" value="$(arg device_ip)"/>
    <arg name="frame_id" value="$(arg frame_id)"/>
    <arg name="manager" value="$(arg manager)" />
    <arg name="model" value="VLP16"/>
    <arg name="pcap" value="$(arg pcap)"/>
    <arg name="port" value="$(arg port)"/>
    <arg name="read_fast" value="$(arg read_fast)"/>
    <arg name="read_once" value="$(arg read_once)"/>
    <arg name="repeat_delay" value="$(arg repeat_delay)"/>
    <arg name="rpm" value="$(arg rpm)"/>
    <arg name="gps_time" value="$(arg gps_time)"/>
    <arg name="cut_angle" value="$(arg cut_angle)"/>
    <arg name="timestamp_first_packet" value="$(arg timestamp_first_packet)"/>
  </include>

  <!-- start transform nodelet -->
  <include file="$(find velodyne_pointcloud)/launch/transform_nodelet.launch">
    <arg name="model" value="VLP16"/>
    <arg name="calibration" value="$(arg calibration)"/>
    <arg name="manager" value="$(arg manager)" />
    <arg name="fixed_frame" value="" />
    <arg name="target_frame" value="" />
    <arg name="max_range" value="$(arg max_range)"/>
    <arg name="min_range" value="$(arg min_range)"/>
    <arg name="organize_cloud" value="$(arg organize_cloud)"/>
  </include>

  <!-- start laserscan nodelet -->
  <include file="$(find velodyne_pointcloud)/launch/laserscan_nodelet.launch">
    <arg name="manager" value="$(arg manager)" />
    <arg name="ring" value="$(arg laserscan_ring)"/>
    <arg name="resolution" value="$(arg laserscan_resolution)"/>
  </include>

</launch>

修改后

<launch>
	<group ns="sensor_b">      <!--主要使用group实现该功能-->
	  <!-- declare arguments with default values -->
	  <arg name="calibration" default="$(find velodyne_pointcloud)/params/VLP16db.yaml"/>
	  <arg name="device_ip" default="192.168.8.201" />
	  <arg name="frame_id" default="velodyne" />
	  <arg name="manager" default="$(arg frame_id)_nodelet_manager" />
	  <arg name="max_range" default="130.0" />
	  <arg name="min_range" default="0.4" />
	  <arg name="pcap" default="" />
	  <arg name="port" default="2368" />
	  <arg name="read_fast" default="false" />
	  <arg name="read_once" default="false" />
	  <arg name="repeat_delay" default="0.0" />
	  <arg name="rpm" default="600" />
	  <arg name="gps_time" default="false" />
	  <arg name="cut_angle" default="-0.01" />
	  <arg name="timestamp_first_packet" default="false" />
	  <arg name="laserscan_ring" default="-1" />
	  <arg name="laserscan_resolution" default="0.007" />
	  <arg name="organize_cloud" default="false" />

	  <!-- start nodelet manager and driver nodelets -->
	  <include file="$(find velodyne_driver)/launch/nodelet_manager.launch">
		<arg name="device_ip" value="$(arg device_ip)"/>
		<arg name="frame_id" value="$(arg frame_id)"/>
		<arg name="manager" value="$(arg manager)" />
		<arg name="model" value="VLP16"/>
		<arg name="pcap" value="$(arg pcap)"/>
		<arg name="port" value="$(arg port)"/>
		<arg name="read_fast" value="$(arg read_fast)"/>
		<arg name="read_once" value="$(arg read_once)"/>
		<arg name="repeat_delay" value="$(arg repeat_delay)"/>
		<arg name="rpm" value="$(arg rpm)"/>
		<arg name="gps_time" value="$(arg gps_time)"/>
		<arg name="cut_angle" value="$(arg cut_angle)"/>
		<arg name="timestamp_first_packet" value="$(arg timestamp_first_packet)"/>
	  </include>

	  <!-- start transform nodelet -->
	  <include file="$(find velodyne_pointcloud)/launch/transform_nodelet.launch">
		<arg name="model" value="VLP16"/>
		<arg name="calibration" value="$(arg calibration)"/>
		<arg name="manager" value="$(arg manager)" />
		<arg name="fixed_frame" value="" />
		<arg name="target_frame" value="" />
		<arg name="max_range" value="$(arg max_range)"/>
		<arg name="min_range" value="$(arg min_range)"/>
		<arg name="organize_cloud" value="$(arg organize_cloud)"/>
	  </include>

	  <!-- start laserscan nodelet -->
	  <include file="$(find velodyne_pointcloud)/launch/laserscan_nodelet.launch">
		<arg name="manager" value="$(arg manager)" />
		<arg name="ring" value="$(arg laserscan_ring)"/>
		<arg name="resolution" value="$(arg laserscan_resolution)"/>
	  </include>
	</group>
</launch>

关键点

主要使用group实现该功能，可以将A的VLP16的launch文件放到

<group ns="sensor_a">......</group>

将B的VLP16的launch文件放到

<group ns="sensor_b">......</group>

即可实现A和B发布的topic不同。