Accel digital spirit-level wanted

Joel Newkirk freerunner at newkirk.us
Sat Nov 29 02:17:17 CET 2008


On Fri, 28 Nov 2008 03:28:32 -0800 (PST), bytestore <bytestore at yandex.ru>
wrote:
> 
> :) Many thanks, I did not know
> 
> 
> Stroller-2 wrote:
>>
>>
>> On 28 Nov 2008, at 07:02, bytestore wrote:
>>> anybody, write programm digital "building" level
>>
>> The English word for this is a digital "spirit level".
>>
>> http://en.wikipedia.org/wiki/Spirit_level
>>
>> HTH,
>>
>> Stroller.

I explored this a couple months ago.  My conclusion was that we didn't get
enough precision and stability from the accelerometers for this purpose,
without smoothing computations I didn't explore.  My testing indicated, for
example, that if the FR is laying on a 4-foot long shelf, you can raise or
lower one end of that shelf by about an inch before being certain via
/dev/input/event3 that you've in fact tilted the FR that direction.  At
about a half-inch it's clear that the values are changing, but the constant
low-level fluctuations drown out your certainty, short of quite a bit more
work (computationally, smoothing and comparing) than I was interested in
putting into the project at the time.

j





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