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Scott Myers
01-26-1995, 01:39 AM
I've developed an accelerometer (3 axis or 1) using the AD50. It is
a very flexible and reliable device, it's my favorate of over 10
different brands. The advantages include it's single chip micromachined
assembly, the on board op amp, a single 5V power supply, an auto test
pin, and a lot of very good application notes. It is designed for the
automotive air bag industry, but that means good news for us, i.e., mass
produced, rigged, very reliable, and competitive in terms of cost and
engineering. In 10,000 lots it's only $5.
In New York I often design instrumentation packages for researchers
or engineers. I've recently discovered the AD50 can be AC coupled. One
problem with accelerometers, especially in low G events, is the effect of
tilt on their output. AC coupling limits the points per second a little,
but eliminates the effect of tilt. In this way human sway or tremor
studies can be carried out. The on board dedicated op amp means the
millivolt/G can be adjusted from the unity gain value of plus or minus
50Gs to plus or minus 2 to 5 Gs.
I make a single and tri axial accelerometer using the AD50 for
$225 and $600 respectively. I include software (LabVIEW) virtual
instruments that are cross-platform (Mac or PC) which analyze and
calibrate the accelerometers. Analysis includes vector force, G force,
jerk, frequency of vibration (tremor), magnitude of tremor, etc. The
virtual instruments are meant to be used with your scaled data acquired
from a data acquisition card, or from a National Instruments LabCARD (PC
or Mac) which I can provide as a package for $1,300. This package would
include virtual instruments with source code (diagrams in LabVIEW lingo))
and optionally LabVIEW Student Edition for $100. LabVIEW Student Edition
is the younger daughter of LabVIEW Full Development System. You can do
almost everything with SE as you can with FDS, it's often messier, less
convenient, but really a good deal. I continue to recommend FDS for
researchers and other major projects, but SE is worth looking into and
I'm offering it as a convenience.
This is intended to be a general discussion of an excellent
accelerometer and techniques to use with accelerometers in biomechanics
studies. However, I can also offer some solutions if you're interested.
Scott Myers
DeskTop Laboratories
12 John Street DP12
New York, NY

---------- Forwarded message ----------
Date: Wed, 25 Jan 1995 15:09:01 -0500 (EST)
From: Clare C Bassile
To: sm205@columbia.edu
Subject: accelerometers (fwd)



---------- Forwarded message ----------
Date: Mon, 23 Jan 1995 11:00:07 -0600
From: Fabian Pollo
To: Multiple recipients of list BIOMCH-L
Subject: accelerometers

Howdy again bio-netters:

Thank you to everyone that reponded to my request for information on
accelerometers. Following is the edited responses that I recieved.


You may try Omega Engineering. I called them yesterday and asked
them the exact same question. They are sending me their catalogs on
various transducers, including accelerometers. Their number is:

1-800-826-6342

Good luck. Please post any of the other replies that you get.
thanks.

Brian Bergemann, Ph.D.
United States Sports Academy
Chairman Sports Research
BWBERGEMANN@USSA-SPORT.USSA.EDU



Fabian--

Another source for accelerometers is:

PCB Piezotronics Inc.
3425 Walden Ave
Depew, NY 14043

716-684-0001

PCB has been an excellent company to work with. They have generally been
willing to help researchers with educational discounts and/or equipment
donations when projects are on "shoe-string" budgets.

Gerald Smith, PhD
Biomechanics Lab, WB-15
Oregon State University
Corvallis, Oregon 97331

email: SMITHG@CCMAIL.ORST.EDU
phone: 1 - 503 - 737 - 5928



Fabian,

I bought a Dytran 3016A triax accelerometer for $950 (10mV/G sensitivity) and
power supply $345 and assorted cable $50 about a year ago.

Dytran Instruments, Inc.
21592 Marilla St.
Chatsworth, CA 91311
(818) 700-7818
In TX they are represented by Jim Bruton of
Technical Products
1023 S. Main Street #203
Grapvine, TX 76051
(817) 424-3441

There are many other companies that make all sizes and kinds of
accelerometers:

Endevco: (800) 982-6732

Entran: (800) 635-0650

Kistler: (716) 691-5100

PCB Piezotronics (716) 684-0001

Duane Knudson, Ph.D.
Department of HHPR
Baylor University


--------------------------------------
Date: 1/20/95 2:35 PM

Here is one company that makes triaxial accelerometers:
ENDEVCO
30700 Rancho Viejo Road
San Juan Capistrano, CA 92675
(714)493-8181


>

You can contact Analog Devices. They make accelerometers for air-bags. It is abo
ut
$50-100 each dependent on quantities.

Jiping
Jiping He, Ph.D.
Associate Professor
Chemical, Bio and Materials Engineering
Arizona State University
Tempe, AZ 85287


Hi Fabian:

There are several companies that make triaxial accelerometers. The
subminiature ones are quite expensive. PCB electronics makes some "cheap"
ones. They will run for between $1000 and $1500 for a triaxial set. The
cheaper accelerometers that you are talking about I was told are rather coarse.
In an airbag design you only need to make sure that above a certain
acceleration the airbag employs, so you don't really care what happens at the
lower end. Kistler makes some excelent accelerometers, but they are rather
expensive.

Ben.

Analog Devices makes two models of uniaxial accelerometers. I think one is
model AD50. ONe model has built in amplifier circuits. I don't know their
address, but they are a large semiconductor company.



>
Try Endevco. They make accelerometers and the instrumentation that
go with them.

-Lynne Bilston
__________________________________________________ ________________________
Lynne E. Bilston, PhD
Department of Mechanical and Mechatronic Engineering Tel (02) 351-2344
Room 426, Building J07 Fax (02) 351-9169
University of Sydney, N.S.W., 2006
AUSTRALIA bilston@tiny.me.su.oz.au
__________________________________________________ ________________________



Dear Fabian

Kistler makes a wide range of accelerometers. Your request for information had
been forwarded to:

Kistler Instrument Corp.
75 John Glenn Drive
Amherst. NY 14228-2171

Tel: (716) 691-5100
Fax: (716) 691-5226


Best Regards


Christian Calame

-----------------------------------------------------------
Kistler Instrumente AG Winterthur, P.O.Box 304,
CH-8408 Winterthur, Switzerland
Tel: +41 52 224 11 11, Fax: +41 52 224 14 14
Telex 896 296 KAG CH,
E-Mail: 100072.1173@compuserve.com
-----------------------------------------------------------


Dear Fabian,

Why don`t you check the Danish Company "Bruel and Kjaer" and Kistler.
B&K`s triaxial accelerometers are highly qualified and miniature in
structure. Also one of the netters had came out with the same question
and I have put her responses to my archive, I will send you the responses
in the nearest time.
I wish you success in your work.

Ozan Akkus


We use uni- and tri-axial accelerometers for examining impulsive
loading during gait. We have typically used IC Sensors and Entran
devices, but we are always looking for smaller and/or less expensive
options. I would be interested in seeing the other responses you receive.

I know of two companies that make inexpensive accelerometers designed
for automotive use, but possibly well suited for biomechanics as well.

1. AMP part no. ACH04-08 (about $40 ea.) measures two linear and one
rotational components, with built-in signal conditioning, designed
for higher-g ranges (> 3g, 125 rad/sec*sec). Sorry - I have no contact
info for AMP.

2. Analog Devices part no. ADXL-10, ADXL-50: single-chip monolithic
design, uni-axial, low-cost, with built-in signal conditioning,
DC-1kHz response, 0-10g or 0-50g range, single +5v supply. Contact
Analog Devices (One Technology Way, P.O. Box 9106, Norwood, MA 02062,
USA) at (617) 329-4700.

We have no experience with the AMP device, but we have experimented a
little with the Analog Devices chip - it looks pretty good so far. We
have talked about trying to assemble a small triaxial system with 3 of
these, but we haven't done anything about it yet.

If anyone has experience with the AMP device, I would be interested in
hearing about it.


************************************************** **********************
Scott Tashman, Ph.D.

Head, Motion Analysis Section Assistant Professor
Bone and Joint Center Department of Orthopaedics
Henry Ford Hospital School of Medicine
2799 W. Grand Blvd. Case Western Reserve University
Detroit, MI 48202

Voice: (313) 876-8680 or 876-7572
FAX: (313) 556-8812 or 876-8064
Internet: tashman@bjc.hfh.edu
************************************************** **********************


Hello Dr. Pollo,

I cannot answer your question about who makes the automobile air bag
accelerometers, but I do have some other company names that are accelerometer
manufacturers. Hope this helps.

Bruel & Kjaer Instuments, Inc.
Marlborough, MA USA
(508) 481-7737

Entran Devices, Inc.
Fairfield, NJ USA
(800) 635-0650

Nat Ordway
Dept of Orthopedics Phone: (315) 464-6462
SUNY Health Science Center Fax: (315) 464-6470
Syracuse, New York USA Email: ordwayn@vax.cs.hscsyr.edu
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100% chance of LIGHTNING. GO CHARGERS!

I hope this helps, it sure helped me.

Thanks again to everyone.

Fabian