simtk.org • RRA large mass adjustments for cycling after normal adjustment for gait trail

Page 1 of 1

RRA large mass adjustments for cycling after normal adjustment for gait trail

Posted: Mon Aug 07, 2017 5:56 pm

by ehhubbar

Hi,

I have gotten expected results for RRA with a subject's gait (walking) experiments. However, when I use kinematic data from a cycling trial, which seems to provide good IK results, I get a recommended mass adjustment of lowering each body segment by about 90% of their masses.

Has anyone seen this sort of recommended mass adjustment with apparently good IK results? I believe the resultant force data would be inaccurate due to F=ma, so I'm wondering if there's a way to correct for this.

Thanks,

Emily

Re: RRA large mass adjustments for cycling after normal adjustment for gait trail

Posted: Wed Aug 09, 2017 9:10 am

by jimmy

It sounds like you are not applying any forces to the model. During walking, you can only perform RRA when all the ground reaction forces are accounted for. For cycling, you would need forces from the pedals, the seat, and the handle bars (if being used) to perform a suitable RRA analysis.