Re: shock detection
- From: "Jon Slaughter" <Jon_Slaughter@xxxxxxxxxxx>
- Date: Mon, 12 Nov 2007 09:08:31 -0600
"Michael" <mk5778@xxxxxxxxx> wrote in message
news:1194873776.715816.160370@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I need to find a way to detect whether our hand held instrument ($25k-
$40k) was abused (dropped, bumped, etc).
It means free fall and shock detection (detect, timestamp, go back to
sleep). First one is relatively simple. "Relatively" because this
shock_detection_system needs to rely on it's own battery - the
instrument may be dropped when main battery is out and this "battery
out" state may be as long as two months. And occupy no (ok, very low)
volume.
Shock detection is what I need help with. I found out (http://
www.isthq.com/main.asp?a=2&b=0&pageid=86&view=active) that 25G is
"small" shock. This gives some clues - shock detector will not
necessarily be able to see free fall - two different devices - ???
"...You have a tough job ahead of you. I know of no technology that
will get you the kind of low power performance you want without a lot
of pain. We do not offer anything like that...." - response from the
accelerometer manufacturer tech support.
I have EE background and my knowledge of physics is limited.
To add insult to the injury: we do not know how much shock our
instrument can sustain without losing performance.
Can anybody point me in the right direction?
How do you plan on measuring free fall? This is probably impossible for
you. Netwon and Einstein say that free fall is an inertial frame of
reference so there is no method that can measure it directly. Any method
doing so must use something about the surroundings(which almost surely = air
resistance).
In any case if your handhelds cost $25k+ then I'm sure you make enough money
so that you can hire someone to try and solve the problem.
As far as impact, which seems to be what you actually need, take a look at
http://en.wikipedia.org/wiki/G-force
http://en.wikipedia.org/wiki/Shock_%28mechanics%29
http://en.wikipedia.org/wiki/Impact_force
But again, if your selling a "handheld" for $25k+(what, is it made of solid
gold?) then you can afford to hire a real scientist to do the work(or are
you that "scientist" that was hired?).
.
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