Scaling Tool gives me strange joint angle

Kaiwen Yang · Post by **Kaiwen Yang** » Sun Dec 16, 2018 7:31 pm

Hi all,

I am scaling an arm model and subject's static pose expected to have an elbow flexion angle of 0 degree. However, scaling tool gives me an angle about 359 degree. What possibly can be the problem here?

Thanks!

Dimitar Stanev · Post by **Dimitar Stanev** » Mon Dec 17, 2018 1:32 am

The arm model is constrained to the ground, and if the marker data are transformed differently then the model will achieve a wrong position. Try to visualize the marker data (File->Preview Experimental Data) to understand the problem. The solution would be to permit the arm model to rotate and move with respect to the ground frame. This can be achieved by adding a free joint between the ground and "base" body.

Kaiwen Yang · Post by **Kaiwen Yang** » Mon Dec 17, 2018 11:50 am

Hi Dimitar,

I think I carefully did the experimental marker rotation so that they match the orientation of the model and thorax fixing to the ground is desirable in my model since we instructed the subject in the experiment to do so.

I guess my confusion is 359 degree is not different than -1 degree. The entire static pose after scaling looks right and marker error is small. However, why not scaling tool give me -1 degree? Even if I set the elbow flexion range from -10 to 130, it still giving me 359 degree on elbow

Dimitar Stanev · Post by **Dimitar Stanev** » Sat Dec 29, 2018 4:24 am

You can find the previous releases on the download page

https://simtk.org/frs/download_confirm. ... roup_id=91

Scaling Tool gives me strange joint angle

Scaling Tool gives me strange joint angle

Re: Scaling Tool gives me strange joint angle

Re: Scaling Tool gives me strange joint angle

Re: Scaling Tool gives me strange joint angle