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由于市面上买的激光雷达价格太贵了。所以在学习时会造成很大的经济压力。但是最近好多做机器人核心组件的公司都开发有廉价的雷达；

本博客教你如何 使用rplidar发布scan数据，在rviz视图中查看scan数据。

1.首先确保你的rplidar水平放置在你的机器人上：(注意安装方向)

2.然后下载rplidar的rosSDK开发包，

3.初步测试：

运行roscore

roscore ＆

直接运行rplidar的launch文件

roslaunch rplidar_ros view_rplidar.launch

 查看view_rplidar.launch文件

 主要是查看rplidar.launch文件

 在这个launch文件中打开了rplidarNode这个节点，然后我们分析一下节点源码：

#include "ros/ros.h"#include "sensor_msgs/LaserScan.h"#include "std_srvs/Empty.h"#include "rplidar.h" //RPLIDAR standard sdk, all-in-one header#ifndef _countof#define _countof(_Array) (int)(sizeof(_Array) / sizeof(_Array[0]))#endif#define DEG2RAD(x) ((x)*M_PI/180.)using namespace rp::standalone::rplidar;RPlidarDriver * drv = NULL;void publish_scan(ros::Publisher *pub,                   rplidar_response_measurement_node_t *nodes,                   size_t node_count, ros::Time start,                  double scan_time, bool inverted,                   float angle_min, float angle_max,                   std::string frame_id){    static int scan_count = 0;    sensor_msgs::LaserScan scan_msg;    scan_msg.header.stamp = start;    scan_msg.header.frame_id = frame_id;    scan_count++;    scan_msg.angle_min =  M_PI - angle_min;    scan_msg.angle_max =  M_PI - angle_max;    scan_msg.angle_increment =         (scan_msg.angle_max - scan_msg.angle_min) / (double)(node_count-1);    scan_msg.scan_time = scan_time;    scan_msg.time_increment = scan_time / (double)(node_count-1);    scan_msg.range_min = 0.15;    scan_msg.range_max = 6.;    scan_msg.intensities.resize(node_count);    scan_msg.ranges.resize(node_count);    if (!inverted) { // assumes scan window at the top        for (size_t i = 0; i < node_count; i++) {            float read_value = (float) nodes[i].distance_q2/4.0f/1000;            if (read_value == 0.0)                scan_msg.ranges[i] = std::numeric_limits
     
      ::infinity();            else                scan_msg.ranges[i] = read_value;            scan_msg.intensities[i] = (float) (nodes[i].sync_quality >> 2);        }    } else {        for (size_t i = 0; i < node_count; i++) {            float read_value = (float)nodes[i].distance_q2/4.0f/1000;            if (read_value == 0.0)                scan_msg.ranges[node_count-1-i] = std::numeric_limits
      
       ::infinity();            else                scan_msg.ranges[node_count-1-i] = read_value;            scan_msg.intensities[node_count-1-i] = (float) (nodes[i].sync_quality >> 2);        }    }    pub->publish(scan_msg);}bool checkRPLIDARHealth(RPlidarDriver * drv){    u_result     op_result;    rplidar_response_device_health_t healthinfo;    op_result = drv->getHealth(healthinfo);    if (IS_OK(op_result)) {         printf("RPLidar health status : %d\n", healthinfo.status);                if (healthinfo.status == RPLIDAR_STATUS_ERROR) {            fprintf(stderr, "Error, rplidar internal error detected."                            "Please reboot the device to retry.\n");            return false;        } else {            return true;        }    } else {        fprintf(stderr, "Error, cannot retrieve rplidar health code: %x\n",                         op_result);        return false;    }}bool stop_motor(std_srvs::Empty::Request &req,                std_srvs::Empty::Response &res){  if(!drv)    return false;  ROS_DEBUG("Stop motor");  drv->stop();  drv->stopMotor();  return true;}bool start_motor(std_srvs::Empty::Request &req,                std_srvs::Empty::Response &res){  if(!drv)    return false;  ROS_DEBUG("Start motor");  drv->startMotor();  drv->startScan();;  return true;}int main(int argc, char * argv[]) {    ros::init(argc, argv, "rplidar_node");    std::string serial_port;    int serial_baudrate = 115200;    std::string frame_id;    bool inverted = false;    bool angle_compensate = true;    ros::NodeHandle nh;    ros::Publisher scan_pub = nh.advertise
       
        ("scan", 1000);    ros::NodeHandle nh_private("~");    nh_private.param
        
         ("serial_port", serial_port, "/dev/ttyUSB0");     nh_private.param
         
          ("serial_baudrate", serial_baudrate, 115200);     nh_private.param
          
           ("frame_id", frame_id, "laser_frame"); nh_private.param
           
            ("inverted", inverted, "false"); nh_private.param
            
             ("angle_compensate", angle_compensate, "true"); u_result op_result; // create the driver instance drv = RPlidarDriver::CreateDriver(RPlidarDriver::DRIVER_TYPE_SERIALPORT); if (!drv) { fprintf(stderr, "Create Driver fail, exit\n"); return -2; } // make connection... if (IS_FAIL(drv->connect(serial_port.c_str(), (_u32)serial_baudrate))) { fprintf(stderr, "Error, cannot bind to the specified serial port %s.\n" , serial_port.c_str()); RPlidarDriver::DisposeDriver(drv); return -1; } // check health... if (!checkRPLIDARHealth(drv)) { RPlidarDriver::DisposeDriver(drv); return -1; } ros::ServiceServer stop_motor_service = nh.advertiseService("stop_motor", stop_motor); ros::ServiceServer start_motor_service = nh.advertiseService("start_motor", start_motor); // start scan... drv->startScan(); ros::Time start_scan_time; ros::Time end_scan_time; double scan_duration; while (ros::ok()) { rplidar_response_measurement_node_t nodes[360*2]; size_t count = _countof(nodes); start_scan_time = ros::Time::now(); op_result = drv->grabScanData(nodes, count); end_scan_time = ros::Time::now(); scan_duration = (end_scan_time - start_scan_time).toSec() * 1e-3; if (op_result == RESULT_OK) { op_result = drv->ascendScanData(nodes, count); float angle_min = DEG2RAD(0.0f); float angle_max = DEG2RAD(359.0f); if (op_result == RESULT_OK) { if (angle_compensate) { const int angle_compensate_nodes_count = 360; const int angle_compensate_multiple = 1; int angle_compensate_offset = 0; rplidar_response_measurement_node_t angle_compensate_nodes[angle_compensate_nodes_count]; memset(angle_compensate_nodes, 0, angle_compensate_nodes_count*sizeof(rplidar_response_measurement_node_t)); int i = 0, j = 0; for( ; i < count; i++ ) { if (nodes[i].distance_q2 != 0) { float angle = (float)((nodes[i].angle_q6_checkbit >> RPLIDAR_RESP_MEASUREMENT_ANGLE_SHIFT)/64.0f); int angle_value = (int)(angle * angle_compensate_multiple); if ((angle_value - angle_compensate_offset) < 0) angle_compensate_offset = angle_value; for (j = 0; j < angle_compensate_multiple; j++) { angle_compensate_nodes[angle_value-angle_compensate_offset+j] = nodes[i]; } } } publish_scan(&scan_pub, angle_compensate_nodes, angle_compensate_nodes_count, start_scan_time, scan_duration, inverted, angle_min, angle_max, frame_id); } else { int start_node = 0, end_node = 0; int i = 0; // find the first valid node and last valid node while (nodes[i++].distance_q2 == 0); start_node = i-1; i = count -1; while (nodes[i--].distance_q2 == 0); end_node = i+1; angle_min = DEG2RAD((float)(nodes[start_node].angle_q6_checkbit >> RPLIDAR_RESP_MEASUREMENT_ANGLE_SHIFT)/64.0f); angle_max = DEG2RAD((float)(nodes[end_node].angle_q6_checkbit >> RPLIDAR_RESP_MEASUREMENT_ANGLE_SHIFT)/64.0f); publish_scan(&scan_pub, &nodes[start_node], end_node-start_node +1, start_scan_time, scan_duration, inverted, angle_min, angle_max, frame_id); } } else if (op_result == RESULT_OPERATION_FAIL) { // All the data is invalid, just publish them float angle_min = DEG2RAD(0.0f); float angle_max = DEG2RAD(359.0f); publish_scan(&scan_pub, nodes, count, start_scan_time, scan_duration, inverted, angle_min, angle_max, frame_id); } } ros::spinOnce(); } // done! RPlidarDriver::DisposeDriver(drv); return 0;}
            
           
          
         
        
       
      
     

 

 主要是打开串口读取rplidar的数据，然后发布scan话题。

查看rqt_graph节点视图。