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Al Vangura Jr.
06-21-1998, 10:15 PM
Biomch-l,
Thank you to all who replied to my original posting on instrumentation for
grip/force/pressure sensing on wheelchair pushrims. I received some
valuable leads and would like to post the replies. Several people
responded to the question with references to force/moment measurement of
pushrims. The references were to the SMARTwheel that was developed by the
director of our lab, Dr. Rory Cooper. I want to use the SMARTwheel in
conjunction with grip measurement via thin-film sensors adhered to the
pushrim to begin to understand the role of grip in CTS/Repetitive Strain
Disorder/Compressive Mononeuropathies. For further information on the
SMARTwheel and other wheelchair testing, visit the University of
Pittsburgh's Human Engineering Research Laboratories webpage at
http://www.pitt.edu/~rstherl/.

Do you know ' SMART' wheel?

Maybe this is adopted wheel axle and measure the torque applied the wheel.
But I don't know the mechanics.

I guess you should refer to the paper as below:

Asato KT, Cooper RA, Robertson RN, Ster JF:
SMART Wheels: development and testing of a system for
measuring manual wheelchair propulsion dynamics.
IEEE Trans Biomed Eng 40:1320-1324, 1993.

Wataru Doyo (pHD student)
Dept. of Health Promotion Science II
Post Graduate School of Medicine
Nagoya University JAPAN
tel +81/52-789-3958 (Prof. Yabe)
fax +81/52-789-3957
e-mail doyo@htc.nagoya-u.ac.jp
Al,
we have a variety of pressure sensing materials. please visit our website
and
see Pressurex film and Podiascan mats. WWW.sensorprod.com
Jeffrey Stark
Sensor Products Inc.

Interesting problem with the pushrim...I remember somebody asking about
that a couple years ago...have you tried the BIOMCH-L archives? How about
an instrumented glove?
How do you differentiate grip force from contact force? My understanding
with wheelchair racers is that they use a ballistic hit against the rim,
then roll onto and around their thumb to achieve angular velocity of the
wheels. I don't view this as a grip force, but a contact force, with the
transfer enhanced by the friction between the hand or gloved hand and the
pushrim.
With non-racers the kinematics and kinetics are probably much different.
Thoughts?
Jon Fewster
NIKE Sport Research Lab

Dear Al,

Novel Electronics makes a glove that measures pressure. I have used their
equipment in several different applications and found it to be very
reliable. You can reach them at (612)221-0505.

Mic Dancisak
Concordia University
Department of Kinesiology
275 Syndicate Street North
St. Paul, MN 55104-5494
(612) 603-6175

Hi Al,

I am also looking at the forces exerted on the wheelchair pushrim. Here are
a few of the different ideas that I have heard:
1) A group that includes Cooper and Robertson (I think that's his name) is
using a device called the SMARTwheel which is a wheel with force
transducers mounted in/on the wheel in some fashion....
2) A typical setup that has been quoted in the past by several groups
(can't remember who they are offhand) has four 3-d force transducers
mounted from the handrim to the axle at 0,90,180, 270 degrees. This way you
should be able to measure the forces on the handrim in any direction at any
point in time
3) There was a description of a pressure sensing glove used by
obstetricians to determine the amount of force that is exerted on a babies
head during delivery in the ASME proceedings (around '89, I think). Has the
potential to be used for determining the pressures, mind you there would be
some problems as to the applicability of this since the force vector
components need a certain reference frame that remains stable in 3-D space
I.e. the handrim(stable) vs.. the hand (can occupy any position in any
orientation in space).
4) Is there any type of pressure sensitive wrap or anything out on the
market that you could place on the handrim of the wheelchair??? You would
figure in this era of miniaturization and 'high' technology that something
like that would exist (Thinking of an idea based roughly along the lines of
the EMED shoe insert system, but not for shoes ;-) )

Hopefully this gives you something to work with. I'd be interested in
hearing the other suggestions you get. If possible could you send me a copy
of the summary of responses, it would be greatly appreciated.
Thanks,
Dan Magnusson
dan@kin.ucalgary.ca

HI,
Here at mayo, we developed an instrumented wheel to measure the hand
reaction forces and moments in 3D. The paper is in galley proof stage for
publication in the journal of biomechanical engineering. You can check our
abstract paper published in "Proceedings of the 1997 Bioengineering
Conference", ASME, Sun River, Oregon, pp329-330.
You can also check out Cooper group's papers. Typical one is Asato Kt,
Cooper RA, Robertson RN and Ster JF (1993) Smart Wheels. IEEE Trans.
Biomed. Eng 40:1320-1324.
Good luck.
KJK
Kyu-Jung Kim, Ph.D. : kimk2@mayo.Edu
Home : 4311 13th Avenue NW, Rochester, MN 55901 (507) 289-6641
Office : Orthopedic Biomechanics Laboratory
Mayo Clinic/Mayo Foundation, 128 Guggenheim Bldg Rochester, MN 55905
(507) 284-4294, (507) 284-5392(FAX)

Hello Al,

Try the emed pressure mat (NOVEL). Works very well.
Greetings
Thomas L. Milani, Ph.D.
BASiS Insitute, Boulder
TUV Product Service
Tel 1 303 402 5277
Fax 1 303 449 3004
Main 1 303 786 7999

e-mail tmilani@tuvps.com
tmilani@hotmail.com
http://www.tuvps.com
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Al,

Why not just unfasten one of the current pushrims on one of the
Smartwheels, and fasten the pushrim of interest. We used to test two
pushrims at once during certain studies with the Smartwheel, swapping them
midway through the test, so the Smartwheel is capable of being retrofit
with nearly any pushrim. Or are you specifically trying to find an
alternative to the Smartwheel?
Brad Lawrence
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It may be possible to adhere pressure sensitive film (piezo-resistive, the
same thing found in pressure sensing seating mats) to the points of
interest (such as the inside and outside circumference of the pushrim). Or
if you are just measuring static loads, some type of deformable plastic
coating could be used. If you knew this material's stiffness and damping
properties, you could measure the deflection (indentation) from a user's
grip and calculate force. This is a challenging project. I'd start by
doing a web search on piezos.
Brad
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Dear Al,
AMTI model MC3 force transducers have been used for this purpose. Please
feel free to contact me for more information.
Best Regards,
Gary Blanchard
Product Manager

AMTI
176 Waltham St., Watertown, Massachusetts 02172-4800
Tel: (800) 422-2684 or (617) 926-6700
Email: garyb@amtimail.com
Fax : (617) 926-5045
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