fluxgate compass, auto calibration, some math

Jan Panteltje · 2011-06-15T19:33:58+00:00

It proved tricky to get 100 % correct calibration of the mag_pic fluxgatecompass.And even then there is some thermal drift from day to night.For something that actually moves, like a compass on a boat for example,it is possible to do auto-calibration that eliminates any offset and gaindifferences for the x and y channel.( East West and North South channel).For those interested I found a nice website with a pdf that describes the mathneeded for auto calibration: have different kind of sensor for sale, and I am working on how those aredesigned,seems to me those sensors use a magnetic bias, as they are lower in frequencyfor north and higher for south sort of thing.Maybe just an LC oscillator with DC flowing in the coil around a highpermeability core, Ic then provides the bias (wild guess).I did some lab test, I can make my own, but not get their sensitivity (yet).Anyways the 'auto calibration' procedure is universal, and I could not resist totry to write the C code.It has some interesting mathematical stuff in it, like Gaussian elimination fora n x n matrix, I found on some site.The C code now works with (their) test vectors, and parses mag_pic output,but is not finished in any way, but may be of interest to some.

Jun 15, 2011 22 Replies

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Michael A. Terrell 15 years ago

Firefox 5.0 is the current version.

It's easy to think outside the box, when you have a cutting torch.

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josephkk 15 years ago

I saw references to it already. I'll bet that it a) won't run on win98 and b) that the slobs will again try to jam it at that machine.

?-(

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Michael A. Terrell 15 years ago

a) Windows Operating Systems

Windows 2000 Windows XP Windows Server 2003 Windows Vista Windows 7

Please note that while the 32-bit and 64-bit versions of Windows Vista and Windows 7 can be used to run Firefox 5, only 32-bit builds of Firefox 5 are supported at this time. Recommended Hardware

Pentium 4 or newer processor that supports SSE2 512MB of RAM 200MB of hard drive space

b) Probably, like everyone else. At least they tell you what you need to run it, before you download it. Unlike some other programs.

It's easy to think outside the box, when you have a cutting torch.

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