鐳神激光雷達對於Autoware的適配

1. 前言

我們的自動駕駛采用鐳神激光雷達，在使用Autoware的時候，需要對鐳神激光雷達的底層驅動，進行一些改變以適配Autoware。

 

2. 修改

（1）首先修改lslidar_c32.launch文件：

<launch>

  <node pkg="lslidar_c32_driver" type="lslidar_c32_driver_node" name="leishen_lslidar_c32_driver" output="screen" >
    <param name="frame_id" value="laser_link"/>
    <param name="device_ip" value="192.168.1.200"/>
    <param name="device_port" value="2368"/>
  </node>

  <node pkg="lslidar_c32_decoder" type="lslidar_c32_decoder_node" name="leishen_lslidar_c32_decoder" output="screen">
    <!-- <param name="child_frame_id" value="world"/> -->
    <param name="child_frame_id" value="velodyne"/>
    <param name="point_num" value="2000"/>
    <param name="channel_num" value="0"/>
    <param name="angle_disable_min" value="0"/>
    <param name="angle_disable_max" value="0"/>
    <param name="min_range" value="0.15"/>
    <param name="max_range" value="500.0"/>
    <param name="frequency" value="10.0"/>
    <param name="publish_point_cloud" value="true"/>
    <param name="publish_channels" value="false"/>
    <remap from="lslidar_point_cloud" to="/points_raw" />
  </node>
  
  <!--node name="rviz" pkg="rviz" type="rviz" args="-d $(find lslidar_c32_decoder)/launch/lslidar_c32.rviz" output="screen"/-->

</launch>

這里貼出了修改后的launch文件，第10行修改為11行，21行去掉s。我們修改了frame_id，將之前的“world”改為“velodyne”。還有就是Autoware需要的點雲topic為points_raw，而鐳神的點雲topic為point_raw，我們講point_raw改為points_raw。

 

（2）修改時間戳

根據鐳神的手冊：“如果鐳神接入GPS，那么會采用GPS時間，如果不接入GPS，雷達會采用內部時間，從0開始以微秒為單位計數，計數值賦值到主數據流時間戳的字節，計數到1小時在從0開始”。這樣會導致在使用TF變換的時候時間戳出錯，所以，需要修改時間戳，找到如下代碼

void LslidarC32Decoder::publishPointCloud() {
//    pcl::PointCloud<pcl::PointXYZI>::Ptr point_cloud(
//                new pcl::PointCloud<pcl::PointXYZI>());
    VPointCloud::Ptr point_cloud(new VPointCloud());

    //point_cloud->header.stamp =
            //pcl_conversions::toPCL(sweep_data->header).stamp;
    point_cloud->header.frame_id = child_frame_id;
    point_cloud->height = 1;

    for (size_t i = 0; i < 32; ++i) {
        const lslidar_c32_msgs::LslidarC32Scan& scan = sweep_data->scans[i];
        // The first and last point in each scan is ignored, which
        // seems to be corrupted based on the received data.
        // TODO: The two end points should be removed directly
        //    in the scans.
        // point_time unit is sec
        double timestamp = point_time;
        //point_cloud->header.stamp = static_cast<uint64_t>(timestamp * 1e6);
        point_cloud->header.stamp = ros::Time::now().toSec() * 1e6; 
        if (scan.points.size() == 0) continue;
        size_t j;
        VPoint point;
        for (j = 1; j < scan.points.size()-1; ++j) {
            point.timestamp = timestamp - (scan.points.size()-1 - j)*0.00005;  // time interval for each point is 50us
            point.x = scan.points[j].x;
            point.y = scan.points[j].y;
            point.z = scan.points[j].z;
            point.intensity = scan.points[j].intensity;
            point.range = scan.points[j].distance;
            point.h_angle = scan.points[j].azimuth;
            point.v_angle = layer_altitude[i];
            point.laserid = layer_id[i];

            point_cloud->points.push_back(point);
            ++point_cloud->width;
        }

    }

    //      if(point_cloud->width > 2000)
    {
        point_cloud_pub.publish(point_cloud);
    }


    return;
}

同樣是貼上修改后的代碼，將19行變為20行。