Question

我试图从pixhawk中获取GPS时间。我发现了很多关于此类问题的讨论，但似乎都没有得到解决。有更新吗？

This家伙和this家伙被告知只使用系统时间（不是UTC）我也试图获得GLOBAL_POSITION_INT_COV，但发现它不可用。

Here是一个长期的讨论，关于这种情况从未得到解决（大约在2013年）

Another开发讨论引用了大量的拉请求 - 但是看起来他们中的任何一个都没有进入或者我错了吗？

非常感谢！

Answer 1

如您的第二个链接所述，ArduPilot会在SYSTEM_TIME消息中发送unix时间。您没有提到您正在使用的语言，但在Python中，使用datetime模块可以轻松地将unix时间转换为UTC。

@vehicle.on_message('SYSTEM_TIME')
def listener(self, name, message):
    unix_time = (int) (message.time_unix_usec/1000000)
    print(datetime.datetime.fromtimestamp( unix_time ))

Answer 2

GPS times reported in MAVLink messages are in two parts: The GPS week number, and the number of milliseconds since the start of that week. Also, need to know when GPS weeks started (Jan 6, 1980).

Here's a bit of javascript code that seems to work well for me (could easily be ported to other languages):

// no. of milliseconds in a date since midnight of
// January 1, 1970, according to UTC time;
// months are zero-based, but days are 1-based
var GPS_EPOCH_MILLIS = (new Date(1980, 0, 6, 0, 0, 0, 0)).getTime();

// all the leap seconds that have been defined so far;
// must keep this list current!
var leapSecondsMillis = [
    (new Date(1981, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1982, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1983, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1985, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1988, 0, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1990, 0, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1991, 0, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1992, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1993, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1994, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1996, 0, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1997, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(1999, 0, 1, 0, 0, 0, 0)).getTime(),
    (new Date(2006, 0, 1, 0, 0, 0, 0)).getTime(),
    (new Date(2009, 0, 1, 0, 0, 0, 0)).getTime(),
    (new Date(2012, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(2015, 6, 1, 0, 0, 0, 0)).getTime(),
    (new Date(2017, 0, 1, 0, 0, 0, 0)).getTime()
];

// convert GPS time to a date & time object
var gpsTimeToDate = function(gpsWeek, millisIntoGPSWeek) {
    return new Date(gpsTimeToMillis(gpsWeek, millisIntoGPSWeek));
};

// 604,800 seconds in a week (60 x 60 x 24 x 7)
var gpsTimeToMillis = function(gpsWeek, millisIntoGPSWeek) {
    var millis = GPS_EPOCH_MILLIS + (gpsWeek * 604800000) + millisIntoGPSWeek; 

    // add leap seconds as appropriate
    for (var leap in leapSecondsMillis)
        if (millis >= leap)
            millis -= 1000;

    return millis;
};

将这些GPS时间用于mavlink的任何尝试都取得了成功吗？

2 个答案: