GaitUniMiami model - gaitapplication2

Congratulations on the new forum - it looks great!
My question relates to gaitapplication2. I have inputted the Vaughn gait data into the GaitUniMiami model. The model runs, but the optimized marker data is a bit off for the right foot. I’ve tried putting the original position of the model very close to the marker data and changing the segment lengths, but every time I run gaitapplication2, the optimization moves the markers further away from the skeleton. Is there another strategy I can use to get the optimization results closer to where they should be?

Hi Abra

Welcome to the forum, glad you like it.

Sometimes the optimization routine gives solutions where the markers are quite far from the bone, even though this looks wrong this solution is the one giving smallest error. The reason can be that the subject had different joint axes orientations and these are not part of this optimization, so it has to compensate for this by moving the markers. Also the stiff foot segment gives a difference between the subject and the model kinematics and will lead to different marker positions.

You have the option to restrict the marker from moving in the individual directions wrt to the bone coordinate system, if you look in the modelgait.txt file for each marker there is a line this

MARKER LKNE 1 -2.941273175400000e-002 -2.286222988233000e-001 -1.083740945580000e-001 weightdummy.txt LKNE.txt dummy.txt dummy.txt on on on

here "on on on " means that the optimizer is allowed to move the marker in x y and z direction during the optimization.

If you have certain direction you would like to restrain you can set this to off, remember that the directions refers to the segment coordinate system on which the marker is attached.

Hope this helps

Best regards
Søren, AnyBody Support

Hi Soeren,
Thanks for your help. I have gotten the foot markers to a more plausible location. However, I have another question regarding gaitapplication2. I have motion capture data for a jump landing, but I only have data for the right leg. Is it still possible to run this data into gaitapplication2 if I give the left leg a set of data points that holds it in one position, or will gaitapplication2 only run with gait data?

Hi Abra,

gaitapplication2 can be used together with any kind of motion for the lower extremities. It does not have to be gait.

Regarding a model with only one leg, then I have just uploaded a new version of GaitApplication2 (version 1.8), which includes a model of the right leg and pelvis. Please have a look in the manual for the input specification language - it is in the .zip file together with the application. Please note, that the model is intended to be used together with the TLEM lower extremity model, for which you can find a download link in one of the newsletters

Currently, there is no model in the repository, which uses this one leg model, so if you want to you use, you will have to make a similar interface setup as in GaitUniMiami. Unfortunately, this is not a simple task.

However, in the upcomming repository, which is expected to be released in a couple of weeks, the model you need is included, so if you are not in a hurry, I would recommend that you wait. If not, then you will have to make the whole interface setup and a new one-leg model based on TLEM

I hope this helps.

Michael Skipper Andersen
AnyBody Technology.