@H_403_1@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.
@H_403_1@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.
@H_403_1@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.
@H_403_1@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.
@H_403_1@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.
@H_403_1@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”.
@H_403_1@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.
@H_403_1@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.
@H_403_1@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.
@H_403_1@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)：
@H_403_1@
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
@H_403_1@On the ISS the AstroPi orientation is that the Ethernet + USB ports face the deck and the SD card slot is towards the sky.
- 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.
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.
@H_403_1@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 @H_403_1@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. @H_403_1@07008 @H_403_1@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). @H_403_1@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. @H_403_1@07009 @H_403_1@So,I am guessing you want to normalise the angled measurements so it looks like they were taken by a device aligned North/South?
最佳答案
我认为您需要创建类似于NEH(北,东,高/海拔/上)的局部参考坐标系,例如
@H_403_1@> Representing Points on a Circular Radar Math approach.
@H_403_1@它在航空中通常用作参考系(标题是从中得出的),因此参考系是根据地理位置及其指向北,东和上的轴计算的.
@H_403_1@现在的问题是,北/南对齐并正常化是什么意思？
@H_403_1@如果参考设备仅测量投影,则您需要执行以下操作：
@H_403_1@
a(ax,ay,az)-加速度 @H_403_1@现在F是B的大小,因此其旋转不变： @H_403_1@
原文链接：https://www.f2er.com/python/533075.htmldot(measured_vector,reference_unit_direction)
@H_403_1@The geomagnetic field vector,B,is described by the orthogonal@H_403_1@这不是我的专业领域,所以我在这里可能是错的,但这是我的理解方式： @H_403_1@B(Bx,By,Bz)-磁场矢量
components X (northerly intensity),Y (easterly intensity) and Z
(vertical intensity,positive downwards);
a(ax,ay,az)-加速度 @H_403_1@现在F是B的大小,因此其旋转不变： @H_403_1@
F = |B| = sqrt( Bx*Bx + By*By + Bz*Bz )
Down = a/|a| // gravity points down
North = B/|B| // north is close to B direction
East = cross(Down,North) // East is perpendicular to Down and North
North = cross(East,Down) // north is perpendicular to Down and East,this should convert North to the horizontal plane
X = dot(North,B)
Y = dot(East,B)
Z = dot(Down,B)
H = sqrt( X*X +Y*Y )