我和我的团队正在参加ESA Astro Pi挑战赛.我们的程序将在ISS上运行3个小时,我们将返回结果并对其进行分析.

我们想研究Sense HAT磁力计的磁强度测量值与世界磁模型(WMM)的预测之间的联系.我们想研究Sense HAT磁力计的准确性.

该程序将从Sense HAT中获取微特斯拉中的原始磁力计数据(X,Y和Z),并按照British geological survey’s article(第2.1节)中的描述计算值H和F.然后,将它们连同使用ephem计算的时间戳和位置一起保存到CSV文件中.

然后,我们将比较来自ISS和WMM的Z,H和F值,并使用我们的数据和差异创建映射(如图6、8和10所示).然后,我们将研究Sense HAT磁力计数据的准确性.

我们想将我们的数据与WMM数据进行比较,以了解Sense HAT磁力计的准确性,但是我们有一个问题,磁力计的方向总是不同的.因此,我们的数据将总是(非常)不同于WMM,因此我们将无法正确比较它们.

我们与Astro Pi支持团队进行了交谈,他们建议“对角度测量进行归一化,以使其看起来像是由对准北/南的设备进行的测量”.

不幸的是,我们(和他们)不知道该怎么做,所以他们建议在Stack Exchange上问这个问题.我在Math Stack Exchange、Physics Stack Exchange和Raspberry Pi Forums上提出了这个问题.无奈地,他们没有收到任何答复,所以我再次提出这个问题.

我们应该怎么做？我们有时间戳,ISS位置(纬度,经度,海拔),磁数据(X,Y和Z)以及从北方的方向的数据.

我们希望对数据进行归一化,以便能够将它们与WMM中的数据正确比较.

这是我们的程序的一部分,该程序计算磁力计的值(未获得归一化的数据)：

compass = sense.get_compass_raw()

try:
    # Get raw data (values are swapped because Sense HAT on ISS is in different position)
    # x: northerly intensity
    # y: easterly intensity
    #  z: vertical intensity
    x = float(compass['z'])
    y = float(compass['y'])
    z = float(compass['x'])

except (ValueError,KeyError) as err:
    # Write error to log (excluded from this snippet)
    pass

try:
    # h: horizontal intensity
    # f: total intensity
    # d: declination
    # i: inclination
    h = sqrt(x ** 2 + y ** 2)
    f = sqrt(h ** 2 + z ** 2)
    d = degrees(atan(y / x))
    i = degrees(atan(z / h))

except (TypeError,ValueError,ZeroDivisionError) as err:
    # Write error to log (excluded from this snippet)
    pass

我们的代码中还有一些简单的模拟器可用：https://trinket.io/library/trinkets/cc87813ce7

来自Astro Pi团队的有关磁力计位置和位置的电子邮件的一部分：

• Z is going down through the middle of the Sense Hat.
• X runs between the USB ports and SD card slot.
• Y runs across from the HDMI port to the 40 way pin header.

On the ISS the AstroPi orientation is that the Ethernet + USB ports face the deck and the SD card slot is towards the sky.
So,that’s basically a rotation around the Y axis from flat. So you keep the Y axis the same and swap around Z and X.

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It can help to look at the Google Street view of the interior of the ISS Columbus module to get a better idea how the AstroPi is positioned;
07007

If you pan the camera down and to the right,you’ll see a green light – that’s the AstroPi. The direction of travel for the whole space station is towards the inflatable Earth ball you can see on the left.

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So,broadly speaking,the SD card slot points towards azimuth as in away from the centre of the Earth (so the X axis).
The LED matrix is facing the direction of travel of the space station (the Z axis).

Because of the orbital path of the ISS the Z and Y axes will continually change direction relative to the poles as it moves around the Earth.

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So,I am guessing you want to normalise the angled measurements so it looks like they were taken by a device aligned North/South?