从xyz磁力计（iPhone 3.0）获得磁北 [英] Getting magnetic north from a xyz magnetometer (iPhone 3.0)

问题描述

我实际上正在重新发布iphone开发板上的一个问题。我没有问过它，但是在试图找到答案时我发现了它。还没有人在那里做出回应，所以我想我会尝试在这里发帖。

I'm actually reposting a question from the iphone development boards. I didn't ask it, but I found it when trying to find its answer. Nobody had yet responded there, so I thought I'd try posting it here.

有没有人知道关于从CLHeading的原始xyz值计算磁航向的算法的任何细节？我相信必须有一个适用于不同磁力计的一般方法。

Does anybody know any specifics about the algorithm of computing the magnetic heading from the raw xyz values of CLHeading? I am sure there must be a general approach to this that works for different magnetometers as well.

推荐答案

如果你不想要使用 trueHeading 值，并假设罗盘完全水平，标题可以这样计算：

If you don't want to use the trueHeading value, and assuming that the compass lies perfectly horizontal, the heading can be computed this way:

• （y> 0）heading = 90 - atan2（x，y）* 180 / pi


• （y< 0）heading = 270 - atan2（x ，y）* 180 / pi


• （y = 0，x< 0）heading = 180.0


• （y = 0，x> 0） heading = 0.0

• (y>0) heading = 90 - atan2(x,y)*180 / pi
• (y<0) heading = 270 - atan2(x,y)*180 / pi
• (y=0, x<0) heading = 180.0
• (y=0, x>0) heading = 0.0

（这些来自 http://www.magneticsensors.com/datasheets/an203.pdf ）

...加上标题必须更正磁偏差和磁偏角

... plus the heading must be corrected for Magnetic deviation and Magnetic declination

如果罗盘不是水平的，你应该只使用水平分量（你不能忽略z轴），将（x，y，z）矢量投影到一个平面上。平行于地球表面，然后根据投影的x和y计算航向。

in case the compass is not horizontal, you should use only the horizontal component (you can not ignore the z axis) by projecting the (x, y, z) vector to a plane that is parallel to the earth surface and then compute the heading from this projected x and y.

希望它有所帮助。

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