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blulrey
05-13-2008, 06:11 AM
Kat,
In response to your original question:
I have not used the accelerometer you mentioned. However our lab has a Biometrics Datalogger, and it works well with Biometrics brand sensors. If you connect sensors that are not Biometrics brand, you have to be sure that the sensors' output is within +/-3V. Maybe this has changed in the newer Datalogger, but that is the sensitivity of the older model.

In response to Chris Kirtley:
This is a timely question for me, as I am in the process of connecting accelerometers to our existing data acquisition equipment. I agree with you that it is a good experience, and it is nice to know every aspect about how they are hooked up. However, I would not be opposed to buying something off the shelf that works, and for two justifiable reasons, neither being laziness!

1. It may not be cheaper in the long run. Sure the actual accelerometers are cheap, but all the supporting material adds up. Wire, connectors, enclosures, soldering iron and tips, solder, de-soldering wick (you know you'll need that!), wire strippers, etc, It all adds up! I have spent $500-$600 on my "inexpensive" accelerometers, I even bought cheap connectors and used some leftover wire from another project. We already have the data acquisition equipment, so for me it is cheaper. For others, it's hard to say. If you add a microcontroller and telemetry system, that would bring the cost up.

2. I am not an electrical engineer, I am a biomechanical engineer. Therefore it is taking much more time. (As the saying goes, "Time is money." In this case, "Time is more tuition.") I am consulting with someone else that knows about electronics every step of the way to make certain I am doing it correctly. When all is said and done, sure I will have learned something, but my degree is not in electronics or electrical engineering, and it does not matter at all for my dissertation whether I build the sensor myself or not. I could have been collecting data awhile ago if I wasn't busy soldering these sensors!

I would suggest to Kat to look at all options. If you have the time and money to do it yourself, and can be fun. If you want to start to collect data as soon as possible, an off the shelf system is the way to go.

Brent Ulrey
PhD Candidate
Occupational Biomechanics Laboratory
University of California, Davis


--- On Tue, 5/13/08, Chris Kirtley wrote:

> From: Chris Kirtley
> Subject: Re: [BIOMCH-L] - 3D Accelerometers
> To: BIOMCH-L@NIC.SURFNET.NL
> Date: Tuesday, May 13, 2008, 6:20 AM
> Dear Kat,
>
> My opinion is that people are too lazy these days - and for
> no justifiable
> reason, since it is so easy to build your own circuits now.
>
> You can buy a 3D accelerometer chip for about $10 and build
> a nice
> microcontroller around it, with flash memory and maybe
> Bluetooth telemetry,
> for not much more. In doing so you will get a much more
> versatile tool and,
> more importantly, will understand every step of how you
> obtain the data.
> This is what universities are for - designing and building
> instruments - not
> buying off-the-shelf products.
>
> I would be interested in what others think!
>
> Chris
>
> On Mon, May 12, 2008 at 10:48 PM, Kat Arbour
> wrote:
>
> >
> > >
> > Hi All-
> >
> > I am planning to research the landing accelerations of
> various high impact
> > jumping skills in an athletic population. Biometrics
> LTD (Model ACL300) has
> > an accelerometer that may be perfect for what I am
> looking for. The
> > accelerometer wires to the datalogger, worn on the
> back, then the athlete is
> > free to do whatever, where ever. (It measures
> acceleration impact-by-impact
> > , its not an "activity monitor" for daily
> caloric expenditure). I am
> > inquiring to see if anyone is familiar with the
> accelerometer and has an
> > opinion about its performance. If you have used it in
> your research, I am
> > very interested in your experiences with it. If you
> have used different
> > accelerometers that allows the subject to be
> untethered, that would be great
> > information, too.
> >
> > Thanks for sharing!
> >
> >
> > Kat Arbour MS MPT
> > PhD student
> > Biomechanics and Movement Science
> > University of Delaware
> > Newark, DE 19716
> >
> >
> >
> >
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> ---------------------------------------------------------------
> >
>
>
>
> --
> Dr. Chris Kirtley MB ChB, PhD
> 608 Dockside
> 44 Ferry St.
> Kangaroo Point
> Queensland 4169
> Australia (GMT+10)
> Tel. 61+7-3891 6644 x 1608
> Fax 3891 6900
>
> West End Family Medical Centre
> Mondays, Tuesdays & Thursday afternoon (07) 3844 4111
>
> Clinical Gait Analysis: http://www.univie.ac.at/cga
> Book:
> http://www.amazon.co.uk/exec/obidos/ASIN/0443100098/203-6674734-4427132
>
>
>
> --
> Dr. Chris Kirtley MB ChB, PhD
> 608 Dockside
> 44 Ferry St.
> Kangaroo Point
> Queensland 4169
> Australia (GMT+10)
> Tel. 61+7-3891 6644 x 1608
> Fax 3891 6900
>
> West End Family Medical Centre
> Mondays, Tuesdays & Thursday afternoon (07) 3844 4111
>
> Clinical Gait Analysis: http://www.univie.ac.at/cga
> Book:
> http://www.amazon.co.uk/exec/obidos/ASIN/0443100098/203-6674734-4427132
>
> ---------------------------------------------------------------
> Information about BIOMCH-L:
> http://www.Biomch-L.org
> Archives:
> http://listserv.surfnet.nl/archives/Biomch-L.html
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