Argus AAD and how it handles for body orientation

[sundevil777 102]

I just realized that I was not giving the guys at Argus enough credit for thinking about measuring different parameters than other AADs do, although I think it might not be so easy to conclude that it is an overall improvement.

Karel Goorts' patent application US2008/0054145 states that they determine the orientation of the jumper in order to improve the accuracy of altitude determination. From the patent application:

3. A device according to claim 2, wherein said magnetometer enables indicating the position and/or orientation of the object or the person to which the parachute is attached during the fall thereof.

4. A device according to claim 1, wherein this device comprises position determination means determining a reference vector used for filtering and adjusting the position of the object in a 3 axis coordinate reference system, whereby the filtering is performed by omitting inaccurate date generated during an inappropriate orientation of the object or person during the fall thereof.

5. A device according claim 4, wherein this device comprises positioning determining means connected to said data processing system and provided for determining a positioning parameter indicating the position and orientation of said object to which said parachute is attached, said data processing system being provided for generating from said positioning parameter a release signal when said instant position filtered value reaches said opening position value.
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It says that the "...the filtering is performed by omitting inaccurate date generated during an inappropriate orientation of the object or person during the fall..."

If they really are "omitting" the data (don't know if that means when back to earth or if that includes vertical) then that is troublesome. It does say "omit" rather than make a correction for, so there could be a lot of missing data, and one might conclude that altitude is determined from the last "valid" data, which might be a long way in terms of altitude and time from the desired activation point.

Even if the data is just "corrected", there are some other possible issues that could result in the unit not activating when intended.

1) What if a rigger installs the unit upside down in the pocket (spun around in the long axis)? This seems like it might be a very easy thing to do, even if instructions are given in the manual, since I think it is true that Argus isn't going out of their way to make it clear that orientation of the unit matters. Perhaps there is something in the design that prevents this.

2) The orientation of the magnetic field does differ at different points in the world, of course especially at the poles. I wonder how the orientation sensor might be misjudging position due to this, perhaps it isn't much unless very near the poles.

3) Sensitivity to other magnetic sources - can it be misguided if you have other magnets nearby including steel plates?

4) Others?

Anyway, it sure is interesting and a search did not show any previous discussion (perhaps I missed it). So, what do you think? What is the potential for error? Is the potential improvement worth the possible error?

Here is a link to the patent application:

http://www.google.com/patents/about?id=nImoAAAAEBAJ&dq=karel+goorts

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[sundevil777 102]

I have been reminded that the Argus doesn't necessarily even utilize the idea as described, so it all may be (probably is?) just be a hypothetical argument about it if it was actually used.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[AndyMan 7]

There is absolutely no reason to think that something as described in a patent even remotely resembles what made it in to the final product.

The patent is an interesting read, but I would not consider it relevant to the operation of the AAD.

_Am

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You put the fun in "funnel" - craichead.