PDA

View Full Version : SUMMARY: Force platform coverings



Peter Sinclair
06-03-2008, 11:47 AM
Dear Biomech-L subscribers,

Thank you to everyone who responded to my request for advice on the use of athletic tracks to cover a force platform.

The major advice was to ensure there is a gap between any covering of the platform and the surrounding surfaces. The material can be attached to the plate using glue, double sided tape or magnets. The best method will vary depending on the material and how it is used, so no comparison could be made between methods.

The other useful information was advice to keep the track flat when stored, rather than in a roll that may not straighten out completely. Also, gaps between the platform covering and surrounding material can be covered using thin tape without significant risk of attenuating horizontal forces.

Thanks once again for your advice. The original posting is below, followed by the full replies I received.

Warm regards,


Peter Sinclair
Faculty of Health Sciences
The University of Sydney
p.sinclair@usyd.edu.au



--------Original Message-------------------------
Dear Colleagues

We have a pair of Kistler force platforms flush mounted in the floor of our laboratory. The work we are about to undertake requires a more compliant surface than our hard laboratory floor and bare platforms; consequently we have a strip of athletics track (Mondo) to be rolled out across the laboratory.

A colleague has suggested that this strip could simply be rolled across both platforms from one end of the laboratory to the other. I expect that this would mean that horizontal forces measured by the platforms would be attenuated through shear forces being supported by the track on either side. The natural solution to this would be to cut holes for the platforms, with pieces of track glued to the platforms and a small gap between the track attached to the platforms and that running across the laboratory on either side.

This method poses a difficulty in aligning the track, however. This product is very heavy and difficult to manoeuvre to exactly the right place. This is an issue for us as we need to lay down and remove the track on each day's testing to accommodate other users of the laboratory.

Does anyone have experience with the use of running tracks in a laboratory where this track is not permanently in place? Do you have a solution that can be easily rolled out and then removed?

Thank you for your kind advice.


Peter Sinclair
Faculty of Health Sciences
The University of Sydney
p.sinclair@usyd.edu.au

------------------------------------------------

make sure, that your plattforms are completely detached from the rest of the floor. Therefore you should cut out the platform sizes from the covering floor (Mondo) in the size of the plates (wit 1 mm of space in between plate and surrounding floor). Fix the peaces with special sticky tape to the platform. Keep the thin space of 1 mm between the force plate and the rest of the floor to be detached physically.

Lars Janshen
Humboldt-University Berlin



I don't have experience working with track but I have used carpet to cover the walking platform, and then cut pieces out of the carpet to cover the platforms. They were glued in place, although the glue didn't really work that well. For a gait study, we didn't really need to permanently fix the pieces. Also if the pieces are cut, with about a .5 cm gap or less around the platforms, then not much motion is lost to material absorption.

Kevin McIntire
Stanford University



We have recently finished testing of different surface and stability of elderly gait. The surfaces were 7.5 meters long and cut into 2.5 meter sections so that they could be easily moved and stored between sessions.
Double sided cello-tape was used to stick the flooring down while still allowing the surfaces to be removed (unlike the stronger carpet tape).

As you mentioned a square piece was cut out and fixed to the force plate again with double side tape to allow measurement of horizontal forces.

You may need to hide the joints between flooring section. For two of the surface the joins between the sections were well hidden (carpet and vinyl), for the third silver duck tape was put across the joint which matched the flooring pattern.

I would store the sections flat rather than rolled up. Storing them flat meant the surface lay flat and true to one another and the ends of the
sections did try to curl up.

Allan Carman
University of Otago



When I did my MPhil at Human Movement Studies at the University of Queensland I used mondo attached to the force plates using magnets. An adhesive backed magnet was attached to the top of the force plate (adhesive side to the force plate) and a similar magnet attached to an aluminium sheet the same size as the force plate and on the other side of the aluminium sheet the underside of the mondo was glued. I am not sure what glue I used but as I recall I spoke to Mondo and they suggested a particular ready available product. See attached method for more details. The only problem I see is if you don't want a thin magnet attached to the top of your force plate all the time. It may work with just 1 magnet attached to the aluminium but AMTI suggested using 2 magnets. The AMTI force plates I used were strain gauge based and I know the Kistler are piezoelectric, I am not sure if this makes a difference. I suggest you run the idea by Kistler and see what they say.

Mark Watts
University of Queensland



We had this very issue with a mondo track when I was at Victoria University. The attached pic is the only one I could find. We had a piece cut to fit the large force plate (piece can be see lying askew at the end of the lead-in mondo, roughly next to where the plate was).

There were 5 pieces in all:
1. Two long lean-in / lead-out pieces that ran right up to the end of the plate (and were rolled out from the plate end, to maintain alignment, aided by double side carpet tape or gaffer tape underneath the edge). One of these long pieces is shown in the photo; the one at the other end is not.
2. One piece over the plate, with double-sided tape underneath.
3. Two side pieces, to fill the width between the edge of the plate and the width of the mondo. Taped to the lead-in / lead-out pieces.

Mondo is indeed heavy and somewhat difficult to move around. We had visions of a mondo roll on wheels, but we never built it. Good luck. :-)

Tim Wriggley
University of Melbourne



I recall having used a wooden top fixed on the top surface of a force platform.
We then had a lot of problems having to recalibrate the stain gage platform every day. We are almost certain that the problem originated from the daily absobtion or evaporation of humidity from the wood. Other fiber material could lead to similar problems

Paul Bourassa
L'Université de Sherbrooke