Question

Python GPS 数据捕获

2017-05-05

2970

python mysql gps

因此，我正在使用 GPS 模块、 Python 和 MySQL 数据库制作一个应用程序。

因此，我编写了一些代码，尝试从 GPS 捕获数据并将其存储在数据库中。我正在使用一个名为“ pynmea2 ”的插件来解析一些数据（经度和纬度）。但是，我需要更多的数据，因此，我已经尝试了很多不同的方法，但我的程序始终崩溃。有人能帮我解决这个问题吗？

大多数时候，我从串行连接获取所有数据，但我希望能够从中删除数据。因此，我得到的示例为： [b'$GPGGA,093512.000,,,,,0,3,,,M,,M,,*47\r\n', b'$GPGLL,,,,,093512.000,V,N*76\r\n', b'$GPGSA,A,1,,,,,,,,,,,,,,,*1E\r\n', b'$GPGSV,3,1,11,15,72,214,,24,52,276,,13,48,141,,17,31,093,29*70\r\n', b'$GPGSV,3,2,11,18,28,292,,28,27,049,25,19,24,120,24,12,23,211,13*7E\r\n', b'$GPGSV,3

好吧，从中提取数据并不是那么简单，但使用 pynmea2 库（唯一我被允许使用的库）效果很好。

所以，我现在需要速度、纬度和经度，但速度现在困扰着我。它给出 ValueError: could not convert string to float: "22*49\\r\\n'" 很多次，因为我没有找到正确的方法来查找数据然后“解析”它。

这是我目前的代码使用；

from model.GPSParser import GPSParser
from model.DB import DB
import serial
import time
import datetime
import pynmea2

#########################################
# This is the main code to setup the
# serial connection with the GPS module.
# it needs to be OR runt as root OR as
# pi with all the root rights.
#########################################
port = "/dev/ttyAMA0"
ser = serial.Serial(port, 9600, timeout=0)

#########################################
# These are all the global variables
# to be used. All defined and set to
# zero or their standard 'Null' value.
#########################################
lat = 0.0
lon = 0.0
cur_speed = 0.0


while True:

    try:
        # Get the data from the serial monitor.
        data = str(ser.readlines()).lstrip("b'")[:-3]
        # print(data)

        #########################################
        # Find the speed, to check if we're
        # standing still or not. Save it in a
        # @var speed
        #########################################
        if data.find('$GPVTG') != -1:
            cur_speed = data.split(",")[7]

        #########################################
        # Get the Latitude and Longitude
        #########################################
        if data.find('$GPGGA') != -1:
            print(data)
            # Check whether the data strings are empty or not.
            if GPSParser.parseLatitude(data) != "" and GPSParser.parseLongitude(data) != "":
                lat = GPSParser.parseLatitude(data)
                lon = GPSParser.parseLongitude(data)
                # Debug printing
                # print("Latitude: " + GPSParser.parseLatitude(data))
                # print("Longitude: " + GPSParser.parseLongitude(data))
                # print("Speed: " + cur_speed)

        #########################################
        # Insert the coordinates into the database
        # Be sure to check of we are really driving
        # So when the speed is higher then 5 km/u
        # Store everything into the database.
        #########################################
        if float(cur_speed) > 5.0:
            db = DB()
            db.insertCoordinates(lat, lon, datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S"))

        # Wait a bit to not overload the Serial port
        time.sleep(0.5)

    ############################################################
    # The error handling
    ############################################################
    except serial.serialutil.SerialException:
        ser.close()
        port = "/dev/ttyAMA0"
        ser = serial.Serial(port, 9600, timeout=0)
        continue
    except pynmea2.ParseError:
        # print("Error on parsing object, continuing...")
        continue
    except BlockingIOError:
        # print("Blocking I/O error, continuing...")
        continue
    except TypeError:
        # print("Type error, continuing...")
        continue
    except IndexError:
        # print("To catch an error...")
        continue
    except KeyboardInterrupt:
        print("\nProgram stopped.")
        exit()

因此，从模型导入不会做太多事情，只有数据库连接，“gps 解析器”只是解析数据字符串然后返回它的 pynmea。

所以我想要的是这样的：

它获取每秒脉冲一次的所有数据，然后将其全部拆分成以 $GP 变量开头的块，然后我可以搜索第二个变量部分，例如 VTG 或 GGA 。然后我可以使用该字符串转换为正确的值，以提取速度、纬度、经度和其他数据（如果需要）。

希望你们能很好地理解我并帮助我。

Answer 1

不确定这是否能解决您的问题，但 pynmea2 具有速度属性，在 talker.py 中定义。

import pynmea2
for i, line in enumerate(open('/tmp/nmea.txt').readlines()):
    # parsing via pynmea
    msg = pynmea2.parse(line.strip())
    if msg.sentence_type == 'VTG':
        print ('parsing line %s with pynmea:' % i, float(msg.spd_over_grnd_kmph))

    # parsing via manually
    if line.startswith('$GPVTG'):
        cur_speed = line.split(",")[7]
        print ('parsing line %s manually:' % i, float(cur_speed))

返回：

parsing line 1 with pynmea: 91.626
parsing line 1 manually: 91.626
parsing line 10 with pynmea: 90.842
parsing line 10 manually: 90.842
parsing line 19 with pynmea: 89.676
parsing line 19 manually: 89.676

Answer 2

我正在开发一个类似的程序，在这个程序中我从 GLL NMEA 语句中收集数据。我使用 try/except 结构来丢弃不完整的数据，这样您就永远不会有空的或损坏的 NMEA 语句。希望它能有所帮助：

# Libraries
import pynmea2
import serial
import io  

# --------------------------------------------------------------------------------------------------------------------------------------------------- #

# Variables
lat_Rover1 = []
lat_Rover2 = []
lon_Rover1 = []
lon_Rover2 = []


# --------------------------------------------------------------------------------------------------------------------------------------------------- #     

# Defining serial port to a variable
# ROVER 1 
serial_port_Rover1 = 'COM3'
ser_Rover1 = serial.Serial(serial_port_Rover1, timeout=3)

# ROVER 2 
serial_port_Rover2 = 'COM4'
ser_Rover2 = serial.Serial(serial_port_Rover2, timeout=3)

sio_Rover1 = io.TextIOWrapper(io.BufferedRWPair(ser_Rover1, ser_Rover1))
sio_Rover2 = io.TextIOWrapper(io.BufferedRWPair(ser_Rover2, ser_Rover2))

# --------------------------------------------------------------------------------------------------------------------------------------------------- #

while True:
    # Reading NMEA data from Rovers
    line_Rover1 = sio_Rover1.readline()
    line_Rover2 = sio_Rover2.readline()
    try:
        msg_Rover1 = pynmea2.parse(line_Rover1, check=False)
        msg_Rover2 = pynmea2.parse(line_Rover2, check=False)
    
    except (pynmea2.ChecksumError, pynmea2.ParseError) as e:
        print("Error parsing data: " + repr(line_Rover1))
        print("Error parsing data: " + repr(line_Rover2))
        
# --------------------------------------------------------------------------------------------------------------------------------------------------- #
#    Appending data to latitude and longitude list values
        
    if msg_Rover1.sentence_type == 'GLL':
        with open("NMEAOutputs_Rover1.txt", "a") as outputs:
            
            # Getting only
            # lat and lon as GLL
                lat_Rover1.append(msg_Rover1.latitude)
                lon_Rover1.append(msg_Rover1.longitude)
                print(msg_Rover1.latitude,";",msg_Rover1.longitude,";", msg_Rover1.timestamp, file=outputs)

    if msg_Rover2.sentence_type == 'GLL':
        with open("NMEAOutputs_Rover2.txt", "a") as outputs:
            
            # Getting only lat and lon as GLL
                lat_Rover2.append(msg_Rover2.lat)
                lon_Rover2.append(msg_Rover2.lon)
                print(msg_Rover2.latitude,";",msg_Rover2.longitude,";", msg_Rover2.timestamp, file=outputs)

要获取速度，您可以使用 VTG NMEA 语句，其中以节为单位显示地速。要解析此数据，您可以使用：

# Filter for only GPS satellites
if msg_Rover1.talker == 'GP':
       # Filter for only VTG NMEA Sentences
        if msg_Rover1.sentence_type == 'VTG':
            print(msg_Rover1.data[4])

我知道您说过要将行拆分成块，然后逐个逗号读取数据。但这是一种更简单的方法。

在此示例中，我将纬度、经度和时间戳值存储在 txt 文件中，但您可以对它们执行任何操作。