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Laura Wood
07-11-2001, 06:09 AM
Thank you to everyone who answered my questions regarding the high speed
camera and accelerometer placement. The following is my original e-mail
with a list of the replies starting with the high speed camera.



For my Master's project, I am researching the effects of head acceleration
in low-speed rear end automobile accidents. I would like to obtain video
footage but I have a limited budget. I need a high speed camera that works
about 100 frames per second. I have searched the archives for any
references to used equpiment. However, my budget is severely limited to
$1000-$2000. I would rather purchase the equipment than rent for several
reasons that need not be in detail. Any information would be greatly
appreciated.

Also, the "controversial position" of the accelerometer on the head has been
the topic of many discussions. I have heard that the bite block is the
"best" way to prevent movement but also that there is new evidence that
there is a lot of mandibular movement and therefore inaccuracy. I am
deciding on where to place the triaxial accelerometer so that it is close to
the head center of gravity. My idea right now is to strap it to the top of
the head and try to minimize the hair movement with something such as a swim
cap. Any help in this area too would be greatly appreciated.

Thank you

Laura


HIGH SPEED CAMERA REPLIES

Dear Laura,
For high speed camera systems , pl. see
www.nacinc.com
but I am not sure of low cost system.
You can also see
www.arielnet.com
Greetings / Atul



Yes, we have a very affordable high-speed camera that goes from 60-250
frames-per-second. This camera, the Redlake MotionMeter, is priced at
$6,995.

In order to provide more information, I would like to learn more about your
high-speed application. What is your application?

Please provide your company's full name, address and phone number.

Please feel free to contact me by phone or e-mail.

I look forward to hearing from you.

Respectfully,
Michael Mongillo
DEL Imaging Systems, LLC
1781 Highland Ave., 2nd Floor
Cheshire, CT 06410
Phone: 203-250-1545
Fax: 203-250-1580




Laura,

The least expensive High Speed video camera on the market today is called
the Motionmeter. You probably saw it on our website. The lowest cost model
is the Motionmeter 250 which costs $6,995. Please feel free to give us a
call if you have any questions.

Thanks for your interest,

Matt Kearney
Tech Imaging Services, Inc.
matt@techimaging.com
617-539-0099
http://www.techimaging.com



Laura,

Usually video picture rates are multiples of the base fram rate
because they increase picture rate by first using individual fields,
then by splitting the field. So, if you live in the UK, you either get
50 pictures/sec (ie uninterlacing the 25 frames/sec) which you can
do using a standard camera, or 100, 200, 400 etc pictures/sec
which you do by dividing each field.

Some new digital video cameras allow you to do high speed
recording, but because they divide up the CCD, the resolution falls
off quickly. The other problem with these cameras is that they often
don't have a stable shutter speed because they don't use an actual
shutter. However, you could see if you could try one of these.
Maybe the supplier would loan one to you, or sponsor the purchase
of one to be within you budget.


Alan Walmsley PhD
Human Performance Centre
School of Physical Education
Division of Sciences
University of Otago
PO BOx 56
Dunedin, New Zealand.
Ph (03) 479 8956, Fax (03) 479 8309
E-mail awalmsley@pooka.otago.ac.nz




Ms. Wood:

The MotionMeter is our most affordable system. I understand that cost is a
concern and would like to offer you a used system, but we do not have one in
stock. However, we do rent this system for $800 per week/$2000 per month,
anywhere in the USA. This rental price can be applied toward a purchase of a
MotionMeter at a later date.

Please let me know if you'd like more information.

Regards,
Michael Mongillo
DEL Imaging Systems, LLC
1781 Highland Ave., 2nd Floor
Cheshire, CT 06410
Phone: 203-250-1545
Fax: 203-250-1580



Laura,

Did you get an opportunity to check the website www.DigitalWestImaging.com
for specifications on a camera that you think would work for you? Our list
is from just under $7k to well over $100k. Your frame rate requirement puts
you into the low end category with remaining things to consider such as:
Desired Resolution, Record media i.e.( Video, S-Video, Digital Stills,
Digital Video ), Environment type, Optics (Distance to Image, Field of View
required), Mounting (Tripod, Ceiling wall etc) and lighting types. Features
of each camera will effect the model that would be best for you. Please
call me to discuss these things and narrow the field. Toll Free (866)
593-1900


Regards,
Mark Green
Mark@DigitalWestImaging.com



Hello Laura,

Thank you for your message. The Ariel Performance Analylsis System (APAS)
is a video-based movement analysis system that operates from the Microsoft
Windows operating system. We currently sell our system with the JVC high
speed digital camcorder. This camera is capable of recording at 60, 120 and
240 Hz. The high speed modes are accomplished by "splitting" the full size
image. For example, at 120 Hz, the full size image is split into halves.
For the 240 Hz mode, the full size image is split into quarters.

The only method to access the high speed images (image-by-image) is to use
the Ariel Software Drivers in conjunction with the APAS system.

There are several methods for purchasing the APAS and I have attached a
current price list for your review. You can also find additional
information on the Ariel internet site (www.arielnet.com).

You can also download the APAS software for a full (and free) 30-day trial
period.

Please review the information and feel free to contact me for any additional
questions.

Sincerely,

John Probe
Ariel Dynamics, Inc.
Email: ARIEL1@ix.netcom.com


ACCELEROMETER REPLIES


Hi,
our biomechanics lab researches shock attenuation and we have used both a
bite-bar and "head gear" for mounting an accelerometer to the head. We also
have experienced problems with the bite-bar (mandibular movement,
high-frequency artifact), and recent research has used the head-gear.
The head-gear is a hard-plastic, adjustable apparatus originally intended
for bracing the heavy mouth-piece and hose assembly of a metabolic analysis
system (might be Douglas Bag era old...). If your university has an
exercise physiology lab, possibly contact them to see if they have one
available. Otherwise, I could e-mail you a picture so you would have an
idea of what to look for/consider.
Cheers!
______________________________

Jason T. Vance, B.S.
Graduate Assistant
Department of Kinesiology
College of Health Sciences
University of Nevada, Las Vegas
4505 Maryland Parkway, Box 453034
Las Vegas, NV 89154-3034
(702)499-5168



Laura:

Numerous studies have been conducted on low-speed, rear-end impacts. I have
seen at least one study that makes such a claim (Weinberg S and Lapointe H
(1987) Cervical extension-flexion injury (whiplash) and internal derangement
of the temporomandibular joint. Journal of Oral and Maxillofacial Surgery,
45 (8): 653-656.), but the dynamics described for the occupant is not
physically possible. None of the other studies report any significant
mandibular movement. This is to be expected since the jaw is closed, or
nearly so, when an occupant is normally seated in a car. In addition, as
the vehicle accelerates forward, the skull is accelerated forward into the
stationary mandible. Since the jaw essentially starts out closed, there is
no motion of the head-mandible system that would tend to open the jaw. If
you have not alread done so, the Society of Automotive Engineers
(www.sae.org) has published several studies concerning on minor rear-end
collisions. Some of these studies and related ones have specifically
addressed this issue. Here are a few selected references that may be of
help. This list is by no means exhaustive. Many other related articles
exist.

Bailey MN, Wong BC, and Lawrence JM (1995) Data and methods for estimating
the severity of minor impacts. Accident Reconstruction: Technology and
Animation V SP-1083, SAE Paper 950352, pp. 139-174.

Emori RI and Horiguchi J (1990) Whiplash in low speed vehicle collisions.
SAE Paper 900542.

Geigl BC, Steffan H, Leinzinger P, Roll, Mühlbauer M, and Bauer G (1994) The
movement of head and cervical spine during rearend impact. SAE Paper
1994-13-0008.

Heise AP, Laskin DM, and Gervin AS (1992) Incidence of temporomandibular
joint symptoms following whiplash injury. Journal of Oral and Maxillofacial
Surgery 50: 825-828.

Howard RP, Benedict JV, Raddin JH, and Smith HL (1991) Assessing neck
extension-flexion as a basis for temporomandibular joint dysfunction.
Journal of Oral and Maxillofacial Surgery, 49(1): 1210-1213.

Howard RP, Hatsell CP, and Guzman HM (1995) Temporomandibular joint injury
potential imposed by the low-velocity extension-flexion maneuver. Journal
of Oral and Maxillofacial Surgery 53: 256-262.

McConnell WE, Howard RP, Guzman HM, Bomar JB, Raddin JH, Benedict JV, Smith
HL, and Hatsell CP (1993) Analysis of human test subject kinematic responses
to low velocity rear end impacts. Vehicle and Occupant Kinematics:
Simulation and Modeling SP-975, SAE Paper 930889, pp. 21-30.

McConnell WE, Howard RP, Van Poppel J, Krause R, Guzman HM, Bomar JB, Raddin
JH, Benedict JV, and Hatsell CP (1995) Human head and neck kinematics after
low velocity rear-end impacts - understanding "whiplash". SAE Paper 952724.

Orner PA (1992) A physician-engineers view of low velocity rearend
collisions. Automobile Safety: Present and Future Technology SP-925, SAE
Paper 921574, pp. 11-17.

Rosenbluth W and Hicks L (1994) Evaluating low-speed rear-end impact
severity and resultant occupant stress parameters. J Forensic Sciences
39(6): 1393-1424.

Scott MW, McConnell WE, Guzman HM, Howard RP, Bomar JB, Smith HL, Benedict
JV, Raddin JH, and Hatsell CP (1993) Comparison of human and ATD head
kinematics during low-speed rearend impacts. Human Surrogates: Design,
Development, and Side Impact Protection SP-945, SAE Paper 930094, pp. 1-8.

Svensson MY, Lövsund P, Håland Y, and Larsson S (1993) The influence of
seat-back and head-restraint properties on the head-neck motion during
rear-impact. SAE Paper 1993-13-0028.

Svensson MY, Lövsund P, Håland Y, and Larsson S (1993) Rear-end collisions -
a study of the influence of backrest properties on head-neck motion using a
new dummy neck. SAE Paper 930343.

Szabo TJ, Welcher JB, Anderson RD, Rice MM, Ward JA, Paulo LR, and Carpenter
NJ (1994) Human occupant response to low speed rear-end impacts. Occupant
Containment and Methods of Assessing Occupant Protection in the Crash
Environment SP-1045, SAE Paper 940532, pp. 23-35.

West DH, Gough JP, and Harper GTK (1993) Low speed rear-end collision
testing using human subjects. Accident Reconstruction Journal, May/June,
5(3): 22-26.


Also, an alternative to conducting crash tests yourself is to hire a firm to
do it for you. I know of at least two reputable firms that conduct such
studies for others on a regular basis. I have done this for my own
low-speed accident research in the past. If you need contact names or phone
numbers, please contact me at the address listed below.

I hope this helps,

Jim Ziegler
_____________________________________
James M. Ziegler, Ph.D.
Ncompass Research, Inc.
jziegler@flash.net

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