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Nancy Black
07-03-1997, 09:58 PM
I'm a doctoral candidate, preparing for thesis experiments, and am faced
with the question of whether to use individual markers mounted on definable
"landmarks" on the upper limbs, or whether one is better using
technical arrays of markers on a common base. While individually mounted
markers are generally self-explanatory (except how to define the
limb segments based on the surface markers), I wonder
how to mount, stabilize and place technical array groupings.
I am assuming the arrays would be placed on the upper arm, forearm and
hand.
My questions are:
1) Schmidt et al. (1994) suggest using "foam rubber", and elsewhere I have
read of neoprene. Sounds HOT. Why not a lighter material like tubigrip
(cotton-rubber bandage material)? Would the flexibility of such a
material allow too much individual marker movement?
2) How are the arrays mounted and stabilized on differently sized arms
- are markers on the arrays moved to be proportionally located similarly
on small and large segments?
- does consistency of marker placement on the "base" material matter if a
"calibration" is made with markers over joints?
- what assumptions of joint centres does such a calibrating technique
include?
3) What information would potentially be lost by using technical arrays
rather than individual markers?

I will be using a 3 camera VICON 140 system for recording arm
movements during activities of daily living.
Your suggestions and comments are most appreciated. I will post a
summary of the replies.

__|~_
Nancy Black __|~_)_I__)_|~_
PhD student, Institute of Biomedical Enineering, University of New Brunswick
+ Ecole de genie )_ __)_|_)__ __)
Universite de Moncton | )____) | EMAIL: blackn@umoncton.ca
Moncton, New Brunswick \\___|____|____|____// FAX: (506) 858-4082
E1A 3E9 CANADA \\ // PHONE: (506) 858-4079
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