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you wrote:
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>I was wondering if anyone has experience with velocity-meters that can be used
>over a short distance 5 yards or so and take pretty rapid samples so velocity
>patterns can be examined. The subject will be human and start from a stationary
>position so the frequence probably does not have to be that great, but I need
>something more accurate than an electronic timer and that I could attach
>probably around the waist or something. The problem with electronic timers is
>that you never know what is triggering them (trunk. hand, arm....)
>
>I looked at using accelerometers but I am afraid of a change in axis when the
>subjects go from a stance to a upright position.
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you can use a force plate as an ergometer that will give you accelerations
of the person's center of mass (and then of course you could integrate to
get the velocity of the center of mass). but that would require already
having a force plate or having to buy/build one.
the other option you might consider is to video tape (hi speed or reg
speed) the subject with markers (and then digitize the markers to get
position and then take the derivative to get velocity), although i have
little to no experience with this latter method. but it would be probably
be easier to set up. you would need a decent camera and decent lighting,
but digitizing software you could probably get for free off the internet
(e.g., NIH Image).
good luck,
Young Hui Chang
------------------------------------------------------------------------------
Young Hui Chang, M.S.
Human Biodynamics Dept. 510-642-2370 (office)
103 Harmon 510-642-8662 (lab)
University of California-Berkeley 510-642-3355 (fax)
Berkeley, CA 94720-4480
----------------"Learning how animals get from here to there."----------------
----------
>I was wondering if anyone has experience with velocity-meters that can be used
>over a short distance 5 yards or so and take pretty rapid samples so velocity
>patterns can be examined. The subject will be human and start from a stationary
>position so the frequence probably does not have to be that great, but I need
>something more accurate than an electronic timer and that I could attach
>probably around the waist or something. The problem with electronic timers is
>that you never know what is triggering them (trunk. hand, arm....)
>
>I looked at using accelerometers but I am afraid of a change in axis when the
>subjects go from a stance to a upright position.
-----------
you can use a force plate as an ergometer that will give you accelerations
of the person's center of mass (and then of course you could integrate to
get the velocity of the center of mass). but that would require already
having a force plate or having to buy/build one.
the other option you might consider is to video tape (hi speed or reg
speed) the subject with markers (and then digitize the markers to get
position and then take the derivative to get velocity), although i have
little to no experience with this latter method. but it would be probably
be easier to set up. you would need a decent camera and decent lighting,
but digitizing software you could probably get for free off the internet
(e.g., NIH Image).
good luck,
Young Hui Chang
------------------------------------------------------------------------------
Young Hui Chang, M.S.
Human Biodynamics Dept. 510-642-2370 (office)
103 Harmon 510-642-8662 (lab)
University of California-Berkeley 510-642-3355 (fax)
Berkeley, CA 94720-4480
----------------"Learning how animals get from here to there."----------------