A question about forward Dynamics (FD)

Ruoli Wang · Post by **Ruoli Wang** » Mon Dec 19, 2011 6:23 am

Hi all,

I have a question about forward dynamics. I want to investigate how joint angles may change when the ankle plantarflexor/dorsiflexor co-contraction is higher than normals in gait. Can forward dynamics do the job? e.g. with pre-defined controls and GRF force data, can FD predict the new kinematics? Should I leave the STATES empty and choose ' solve for equilibrium for actuator states'?

Thanks for your help!

Ruoli

Rudolf Klemetti · Post by **Rudolf Klemetti** » Mon Dec 19, 2011 7:15 am

Hello,

Technically, if you modify controls and/or GRF data, Forward tool will provide new kinematics. Physiological relevance may be an issue though. You should include states file since it sets initial conditions for a simulation. For "solve for equilibrium...", consult Edith Arnold's great reply at https://simtk.org/forums/viewtopic.php?f=91&t=2952

Hope this helps,

Rudi

Ruoli Wang · Post by **Ruoli Wang** » Mon Dec 19, 2011 8:08 am

Hi Rudi,

Thank you for the quick reply.

About states file, will FD give different joint angles than the input .sto? Is it enough just giving states values at the inital time and let it compute forward a short interval?

Thank you,

Ruoli

Rudolf Klemetti · Post by **Rudolf Klemetti** » Mon Dec 19, 2011 10:21 am

Yes, Forward tool computes new states, including new joint angles. And yes, you need just initial states as input states.

Rudolf Klemetti · Post by **Rudolf Klemetti** » Mon Dec 19, 2011 10:41 am

Actually, what I wrote below is true in case you don't employ Corrective Controller.

A question about forward Dynamics (FD)

A question about forward Dynamics (FD)

Re: A question about forward Dynamics (FD)

Re: A question about forward Dynamics (FD)

Re: A question about forward Dynamics (FD)

Re: A question about forward Dynamics (FD)