Alt-BEAM Archive

Message #07920



To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Mon, 22 Nov 1999 22:48:54 -0800
Subject: [alt-beam] Re: two axis accelerometer (was: degrees of freedom)


You would still have a problem : Accelerometers are by definition, =
great for
relative not absolute measurements . If you take the double integral of =
the
outputs as x/y position information, it is subject to "drift" errors.
However if the error is small then only an occasional correction may be
required to reset the internal frame of reference against an absolute
external "landmark". Sound a bit like some kruize misyle doesn't it? =
(see
if lanl snoops pick that up 8^).

Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493=20
fax: (604)590-3411

> -----Original Message-----
> From: Tom Edwards [SMTP:edwards9@hotmail.com]
> Sent: Monday, November 22, 1999 9:25 PM
> To: beam@sgiblab.sgi.com
> Subject: two axis accelerometer (was: degrees of freedom)
>=20
>=20
> >To the contrary, it immediately gave me ideas about
> >measuring the "attitude"
> >of a "bothead". Roll is interesting since it
> >requires a horizon (ie a line)
> >as a reference instead of the point source required
> >for pitch and yaw. So how would you do this?
>=20
> perhaps the Analog Devices ADXL202 would work pretty
> well for this. it is a two axis accelerometer with
> duty cycle modulated outputs and isn't that what kind
> of like what a bicore does? if you fill out their form
> and get "registered" you can get them to send you a
> sample part for free. if we could get someone to buy
> 1000 of them they would only be $16 or so apiece B-}
>=20
> look at
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> http://products.analog.com/products/info.asp?product=3DADXL202
> =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D
> where you will see things like
> =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
> The ADXL202 is a low cost, low power, complete 2-axis
> accelerometer with a measurement range of =B12 g. The
> ADXL202 can measure both dynamic acceleration
> (e.g., vibration) and static acceleration (e.g., gravity).
>=20
> The outputs are Duty Cycle Modulated (DCM) signals whose
> duty cycles (ratio of pulsewidth to period) are proportional
> to the acceleration in each of the 2 sensitive axes.
> =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> some people are soldering these directly into 3COM palm pilots
> so that they can play 'marble in a maze' games. tilt your palm
> forward and the 'ball' falls forward, tilt it back and it falls
> back, that kind of thing.
>=20
>=20
> T
>=20
>=20
>=20
> ______________________________________________________
>


7921 Mon, 22 Nov 1999 23:34:41 -0800 [alt-beam] No Subject alt-beam@eGroups.com w.j.m.brok@stud.tue.nl Dear list,

I sent this message a couple of days earlier as well, a couple of
times, but then I didn't receive it back from the list's server, so I
figured something was wrong. Here it is again via this alt-beam way:

Unfortunately I have to unsubscribe for a while: at the moment I am
really busy with my study and in the beginning of next year I will
start my internship at the Institute of Neuroinformatics in Zurich
(where Susanne Still does her PhD). This means that I am and will be
seriously lacking time to contribute to the list for a while.

However, if any of you thinks that I am the one who can answer a
question or help with something, please mail to me directly
(W.J.M.Brok@stud.tue.nl) and I will do what I can.

Best regards,

Wouter Brok.


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