激光雷达学习笔记（一）数据采集

原文出处：http://blog.csdn.net/renshengrumenglibing/article/details/8596401



激光雷达或者叫激光测距仪数据采集比较简单，有位好心的网友提供了一篇博客专门讲这个，这里就不再赘述，贴出链接，需要的直接去看原文，激光雷达的型号：UTM-30LX。

激光雷达数据采集

当前网上关于激光雷达的资料比较少，毕竟用的人不是很多。开发环境主流的还是C/C++，官方提供的例程也都是C/C++的。

官网资料：http://www.hokuyo-aut.jp/02sensor/07scanner/download/urg_programs_en/ 
上面包括激光雷达的驱动和采集软件都有提供，需要的话只需要按照上面的步骤去做就可以。

虽然激光雷达的型号不同，采集部分的代码不同，但是数据处理部分的方法确实相同的，在接下来的日子里我会逐渐共享我使用激光雷达数据所用到的算法和代码，共同学习，共同进步。

      现在的开发语言是C/C++，控制台程序，为了便于快速实现以及进行图形的显示，使用了OpenCV2.4的代码。当然也有人用Labview或者Matlab开发激光雷达，不同的方法之间各有利弊，同时也看个人的喜好。Labview界面部分很简单快捷，编程效率也很高，但是感觉算法的实现稍微麻烦些；Matlab编程效率高，常用函数齐全。Matlab和Labview开发激光雷达一个共同的问题是程序的可移植性。我更加希望我的程序可以移植到嵌入式平台上，不管是Linux环境或者裸机环境。

激光雷达数据采集程序：（UTM-30LX）

/*!
\file
\brief Sample to get URG data using Win32

\author Satofumi KAMIMURA

$Id: capture_sample.cpp 1724 2010-02-25 10:43:11Z satofumi $

Compling and execute process
- In case of Visual Studio
- Select capture_sample.sln from capture_sample.zip
- When Visual Studio is started, press F5 to build and execute.
- If COM port is not found, then change the com_port in main function.

- In case of MinGW, Cygwin
- % g++ capture_sample.cpp -o capture_sample
- % ./capture_sample
- If COM port is not found, then change the com_port in main function.

\attention Change com_port, com_baudrate values in main() with relevant values.
\attention We are not responsible for any loss or damage occur by using this program
\attention We appreciate the suggestions and bug reports
*/

#define _CRT_SECURE_NO_WARNINGS

#include <windows.h>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>

using namespace std;

// To record the output of SCIP,define RAW_OUTPUT
//#define RAW_OUTPUT

#if defined(RAW_OUTPUT)
static FILE* Raw_fd_ = NULL;
#endif

enum {
Timeout = 1000, // [msec]
EachTimeout = 2, // [msec]
LineLength = 64 + 3 + 1 + 1 + 1 + 16,
};

static HANDLE HCom = INVALID_HANDLE_VALUE;
static int ReadableSize = 0;
static char* ErrorMessage = "no error.";

/*!
\brief Manage sensor information
*/
typedef struct
{
enum {
MODL = 0, //!< Sensor model information
DMIN, //!< Minimum measurable distance [mm]
DMAX, //!< Maximum measurable distance [mm]
ARES, //!< Angle of resolution
AMIN, //!< Minimum measurable area
AMAX, //!< Maximum measurable area
AFRT, //!< Front direction value
SCAN, //!< Standard angular velocity
};
string model; //!< Obtained MODL information
long distance_min; //!< Obtained DMIN information
long distance_max; //!< Obtained DMAX information
int area_total; //!< Obtained ARES information
int area_min; //!< Obtained AMIN information
int area_max; //!< Obtained AMAX information
int area_front; //!< Obtained AFRT information
int scan_rpm; //!< Obtained SCAN information

int first; //!< Starting position of measurement
int last; //!< End position of measurement
int max_size; //!< Maximum size of data
long last_timestamp; //!< Time stamp when latest data is obtained
} urg_state_t;

// Delay
static void delay(int msec)
{
Sleep(msec);
}

static int com_changeBaudrate(long baudrate)
{
DCB dcb;

GetCommState(HCom, &dcb);
dcb.BaudRate = baudrate;
dcb.ByteSize = 8;
dcb.Parity = NOPARITY;
dcb.fParity = FALSE;
dcb.StopBits = ONESTOPBIT;
SetCommState(HCom, &dcb);

return 0;
}

// Serial transceiver
static int com_connect(const char* device, long baudrate)
{
#if defined(RAW_OUTPUT)
Raw_fd_ = fopen("raw_output.txt", "w");
#endif

char adjust_device[16];
_snprintf(adjust_device, 16, "\\\\.\\%s", device);
HCom = CreateFileA(adjust_device, GENERIC_READ | GENERIC_WRITE, 0,
NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

if (HCom == INVALID_HANDLE_VALUE) {
return -1;
}

// Baud rate setting
return com_changeBaudrate(baudrate);
}

static void com_disconnect(void)
{
if (HCom != INVALID_HANDLE_VALUE) {
CloseHandle(HCom);
HCom = INVALID_HANDLE_VALUE;
}
}

static int com_send(const char* data, int size)
{
DWORD n;
WriteFile(HCom, data, size, &n, NULL);
return n;
}

static int com_recv(char* data, int max_size, int timeout)
{
if (max_size <= 0) {
return 0;
}

if (ReadableSize < max_size) {
DWORD dwErrors;
COMSTAT ComStat;
ClearCommError(HCom, &dwErrors, &ComStat);
ReadableSize = ComStat.cbInQue;
}

if (max_size > ReadableSize) {
COMMTIMEOUTS pcto;
int each_timeout = 2;

if (timeout == 0) {
max_size = ReadableSize;

} else {
if (timeout < 0) {
/* If timeout is 0, this function wait data infinity */
timeout = 0;
each_timeout = 0;
}

/* set timeout */
GetCommTimeouts(HCom, &pcto);
pcto.ReadIntervalTimeout = timeout;
pcto.ReadTotalTimeoutMultiplier = each_timeout;
pcto.ReadTotalTimeoutConstant = timeout;
SetCommTimeouts(HCom, &pcto);
}
}

DWORD n;
ReadFile(HCom, data, (DWORD)max_size, &n, NULL);
#if defined(RAW_OUTPUT)
if (Raw_fd_) {
for (int i = 0; i < n; ++i) {
fprintf(Raw_fd_, "%c", data[i]);
}
fflush(Raw_fd_);
}
#endif
if (n > 0) {
ReadableSize -= n;
}

return n;
}

// The command is transmitted to URG
static int urg_sendTag(const char* tag)
{
char send_message[LineLength];
_snprintf(send_message, LineLength, "%s\n", tag);
int send_size = (int)strlen(send_message);
com_send(send_message, send_size);

return send_size;
}

// Read one line data from URG
static int urg_readLine(char *buffer)
{
int i;
for (i = 0; i < LineLength -1; ++i) {
char recv_ch;
int n = com_recv(&recv_ch, 1, Timeout);
if (n <= 0) {
if (i == 0) {
return -1; // timeout
}
break;
}
if ((recv_ch == '\r') || (recv_ch == '\n')) {
break;
}
buffer[i] = recv_ch;
}
buffer[i] = '\0';

return i;
}

// Trasmit command to URG and wait for response
static int urg_sendMessage(const char* command, int timeout, int* recv_n)
{
int send_size = urg_sendTag(command);
int recv_size = send_size + 2 + 1 + 2;
char buffer[LineLength];

int n = com_recv(buffer, recv_size, timeout);
*recv_n = n;

if (n < recv_size) {
// if received data size is incorrect
return -1;
}

if (strncmp(buffer, command, send_size -1)) {
// If there is mismatch in command
return -1;
}

// !!! check checksum here

// Convert the response string into hexadecimal number and return that value
char reply_str[3] = "00";
reply_str[0] = buffer[send_size];
reply_str[1] = buffer[send_size + 1];
return strtol(reply_str, NULL, 16);
}

// Change baudrate
static int urg_changeBaudrate(long baudrate)
{
char buffer[] = "SSxxxxxx\r";
_snprintf(buffer, 10, "SS%06d\r", baudrate);
int dummy = 0;
int ret = urg_sendMessage(buffer, Timeout, &dummy);

if ((ret == 0) || (ret == 3) || (ret == 4)) {
return 0;
} else {
return -1;
}
}

// Read out URG parameter
static int urg_getParameters(urg_state_t* state)
{
// Read parameter
urg_sendTag("PP");
char buffer[LineLength];
int line_index = 0;
enum {
TagReply = 0,
DataReply,
Other,
};
int line_length;
for (; (line_length = urg_readLine(buffer)) > 0; ++line_index) {

if (line_index == Other + urg_state_t::MODL) {
buffer[line_length - 2] = '\0';
state->model = &buffer[5];

} else if (line_index == Other + urg_state_t::DMIN) {
state->distance_min = atoi(&buffer[5]);

} else if (line_index == Other + urg_state_t::DMAX) {
state->distance_max = atoi(&buffer[5]);

} else if (line_index == Other + urg_state_t::ARES) {
state->area_total = atoi(&buffer[5]);

} else if (line_index == Other + urg_state_t::AMIN) {
state->area_min = atoi(&buffer[5]);
state->first = state->area_min;

} else if (line_index == Other + urg_state_t::AMAX) {
state->area_max = atoi(&buffer[5]);
state->last = state->area_max;

} else if (line_index == Other + urg_state_t::AFRT) {
state->area_front = atoi(&buffer[5]);

} else if (line_index == Other + urg_state_t::SCAN) {
state->scan_rpm = atoi(&buffer[5]);
}
}

if (line_index <= Other + urg_state_t::SCAN) {
return -1;
}
// Calculate the data size
state->max_size = state->area_max +1;

return 0;
}

/*!
\brief Connection to URG

\param state [o] Sensor information
\param port [i] Device
\param baudrate [i] Baudrate [bps]

\retval 0 Success
\retval < 0 Error
*/
static int urg_connect(urg_state_t* state,
const char* port, const long baudrate)
{
static char message_buffer[LineLength];

if (com_connect(port, baudrate) < 0) {
_snprintf(message_buffer, LineLength,
"Cannot connect COM device: %s", port);
ErrorMessage = message_buffer;
return -1;
}

const long try_baudrate[] = { 19200, 115200, 38400 };
size_t n = sizeof(try_baudrate) / sizeof(try_baudrate[0]);
for (size_t i = 0; i < n; ++i) {

// Search for the communicate able baud rate by trying different baud rate
if (com_changeBaudrate(try_baudrate[i])) {
ErrorMessage = "change baudrate fail.";
return -1;
}

// Change to SCIP2.0 mode
int recv_n = 0;
urg_sendMessage("SCIP2.0", Timeout, &recv_n);
if (recv_n <= 0) {
// If there is difference in baud rate value,then there will be no
// response. So if there is no response, try the next baud rate.
continue;
}

// If specified baudrate is different, then change the baudrate
if (try_baudrate[i] != baudrate) {
urg_changeBaudrate(baudrate);

// Wait for SS command applied.
delay(100);

com_changeBaudrate(baudrate);
}

// Get parameter
if (urg_getParameters(state) < 0) {
ErrorMessage =
"PP command fail.\n"
"This COM device may be not URG, or URG firmware is too old.\n"
"SCIP 1.1 protocol is not supported. Please update URG firmware.";
return -1;
}
state->last_timestamp = 0;

// success
return 0;
}

// fail
ErrorMessage = "no urg ports.";
return -1;
}

/*!
\brief Disconnection
*/
static void urg_disconnect(void)
{
com_disconnect();
}

/*!
\brief Receive range data by using GD command

\param state[i] Sensor information

\retval 0 Success
\retval < 0 Error
*/
static int urg_captureByGD(const urg_state_t* state)
{
char send_message[LineLength];
_snprintf(send_message, LineLength,
"GD%04d%04d%02d", state->first, state->last, 1);

return urg_sendTag(send_message);
}

/*!
\brief Get range data by using MD command

\param state [i] Sensor information
\param capture_times [i] capture times

\retval 0 Success
\retval < 0 Error
*/
static int urg_captureByMD(const urg_state_t* state, int capture_times)
{
if (capture_times >= 100) {
capture_times = 0;
}

char send_message[LineLength];
_snprintf(send_message, LineLength, "MD%04d%04d%02d%01d%02d",
state->first, state->last, 1, 0, capture_times);

return urg_sendTag(send_message);
}

// Decode 6bit data
static long urg_decode(const char data[], int data_byte)
{
long value = 0;
for (int i = 0; i < data_byte; ++i) {
value <<= 6;
value &= ~0x3f;
value |= data[i] - 0x30;
}
return value;
}

// Receive range data
static int urg_addRecvData(const char buffer[], long data[], int* filled)
{
static int remain_byte = 0;
static char remain_data[3];
const int data_byte = 3;

const char* pre_p = buffer;
const char* p = pre_p;

if (*filled <= 0) {
remain_byte = 0;
}

if (remain_byte > 0) {
memmove(&remain_data[remain_byte], buffer, data_byte - remain_byte);
data[*filled] = urg_decode(remain_data, data_byte);
++(*filled);
pre_p = &buffer[data_byte - remain_byte];
p = pre_p;
remain_byte = 0;
}

do {
++p;
if ((p - pre_p) >= static_cast<int>(data_byte)) {
data[*filled] = urg_decode(pre_p, data_byte);
++(*filled);
pre_p = p;
}
} while (*p != '\0');
remain_byte = (int)(p - pre_p);
memmove(remain_data, pre_p, remain_byte);

return 0;
}

static int checkSum(char buffer[], int size, char actual_sum)
{
char expected_sum = 0x00;
int i;

for (i = 0; i < size; ++i) {
expected_sum += buffer[i];
}
expected_sum = (expected_sum & 0x3f) + 0x30;

return (expected_sum == actual_sum) ? 0 : -1;
}

/*!
\brief Receive URG data

\param state [i] Sensor information
\param data [o] range data
\param max_size [i] range data buffer size

\retval >= 0 number of range data
\retval < 0 Error
*/
static int urg_receiveData(urg_state_t* state, long data[], size_t max_size)
{
int filled = 0;

// fill -1 from 0 to first
for (int i = state->first -1; i >= 0; --i) {
data[filled++] = -1;
}

char message_type = 'M';
char buffer[LineLength];
int line_length;
for (int line_count = 0; (line_length = urg_readLine(buffer)) >= 0;
++line_count) {

// check sum
if ((line_count > 3) && (line_length >= 3)) {
if (checkSum(buffer, line_length - 1, buffer[line_length - 1]) < 0) {
fprintf(stderr, "line_count: %d: %s\n", line_count, buffer);
return -1;
}
}

if ((line_count >= 6) && (line_length == 0)) {
for (size_t i = filled; i < max_size; ++i) {
// fill -1 to last of data buffer
data[filled++] = -1;
}
return filled;

} else if (line_count == 0) {
if ((buffer[0] != 'M') && (buffer[0] != 'G')) {
return -1;
}
message_type = buffer[0];

} else if (! strncmp(buffer, "99b", 3)) {
line_count = 4;

} else if ((line_count == 1) && (message_type == 'G')) {
line_count = 4;

} else if (line_count == 4) {
if (strncmp(buffer, "99b", 3)) {
return -1;
}

} else if (line_count == 5) {
state->last_timestamp = urg_decode(buffer, 4);

} else if (line_count >= 6) {
if (line_length > (64 + 1)) {
line_length = (64 + 1);
}
buffer[line_length -1] = '\0';
int ret = urg_addRecvData(buffer, data, &filled);
if (ret < 0) {
return ret;
}
}
}
return -1;
}

void outputData(long data[], int n, size_t total_index)
{
char output_file[] = "data_xxxxxxxxxx.csv";
_snprintf(output_file, sizeof(output_file), "data_%03d.csv", total_index);
FILE* fd = fopen(output_file, "w");
if (! fd) {
perror("fopen");
return;
}

for (int i = 0; i < n; ++i) {
fprintf(fd, "%ld, ", data[i]);
}
fprintf(fd, "\n");

fclose(fd);
}

int main(int argc, char *argv[])
{
const char com_port[] = "COM10";
const long com_baudrate = 115200;

urg_state_t urg_state;
int ret = urg_connect(&urg_state, com_port, com_baudrate);
if (ret < 0) {
printf("urg_connect: %s\n", ErrorMessage);
getchar();
exit(1);
}

int max_size = urg_state.max_size;
long* data = new long[max_size];

enum { CaptureTimes = 5 };
size_t total_index = 0;

//////////////////////////////////////////////////////////////////////
printf("using GD command\n");

int recv_n = 0;
urg_sendMessage("BM", Timeout, &recv_n);

for (int i = 0; i < CaptureTimes; ++i) {
urg_captureByGD(&urg_state);
int n = urg_receiveData(&urg_state, data, max_size);
if (n > 0) {
printf("% 3d: front: %ld, urg_timestamp: %ld\n",
i, data[urg_state.area_front], urg_state.last_timestamp);

outputData(data, n, ++total_index);
}
}
printf("\n");

/////////////////////////////////////////////////////////////////////
printf("using MD command\n");

urg_captureByMD(&urg_state, CaptureTimes);
for (int i = 0; i < CaptureTimes; ++i) {
int n = urg_receiveData(&urg_state, data, max_size);
if (n > 0) {
printf("% 3d: front: %ld, urg_timestamp: %ld\n",
i, data[urg_state.area_front], urg_state.last_timestamp);

outputData(data, n, ++total_index);
}
}

if (CaptureTimes >= 100) {
int dummy;
urg_sendMessage("QT", Timeout, &dummy);
}

urg_disconnect();
delete [] data;

printf("end.\n");

getchar();
return 0;
}
//激光雷达采集到数据的显示：