Markers for fatigue biomechanical testing

[Twigs13]

Hi all,

I'm going to be conducting a lot of 3D tests as paart of my PhD and as part of that we would like to test subjects after a 1-2 hour run on a treadmill. We've noticed the standard markers tend to fall off when attached normally, let alone when someone has been sweating profusely. We've looking into reflective paints, visible in the IR spectrum and are also considering using the reflective dots, attached directly to skin, as markers. The theory is that these will remain in place better than our standard double sided tape approach. Because we are looking at fatigue effects it is not feasible to mark the subjects up after the run as this will give them time to recover and limit the fatigue effects visibilty.

I'm just looking for any ideas or feedback I can get on this idea. For example, are the reflective dots available from NaturalPoint accurate and consistent enough to be picked up by ARENA or Motive (we currently have ARENA, but are looking to upgrade).

Cheers,

Kim Andersen
Postgraduate Student - Sports Engineering
University of Adelaide

[NaturalPoint - Brent]

Hi Kim,

One thing you can try is to put a layer of eyelash glue on the skin where the marker is going to be. You can apply the marker directly to the glue or wait for it dry and them put the double sided tape over that. This way a barrier of sorts is created to help stop sweat from making the tape lose it sticking ability.

The sphere markers are the best for tracking. People do use the flat dots but the camera placement is quite crucial as the disks will have less chance of being seen by cameras, unless the cameras are facing the disks straight on.

Also, Motive is a huge upgrade over Arena. Improved calibrations, tracking, and a lot of other features. I highly recommend the upgrade. If you are interested, feel free to send me an email and I can tell you what the upgrade will be.

Thank you,
Brent Mason
Technical Sales Engineer
brent@naturalpoint.com