squat/fall simulation

[Jicheng Xia]

Good morning,

First, thanks the Opensim group for your hard working. Opensim is a great one.

I am just starting with openSim, so I have some rookie questions:
Is it possible to do a squat/fall simulation in openSim and find torques about knee or is it possible to find how much torque is being exerted by muscles about knee to keep human in a certain position? If there is no ready simulation file available in openSim for squat/fall, is it
possible to make one?

Thanks,
Jicheng

[Ajay Seth]

Hi Jicheng:

Yes it is possible to do these simulations. If you have experimental data (markers and GRFs) you can track the motion. It would be good to follow tutorial 3 using the gait2354 example (in the doc and examples subfolders of your OpenSim install). You can apply the torques or use CMC to get muscle excitations and forces.

If you do not have experimental data it might be a bit involved. You will either have to add a contact model or connect (weld, pin) the feet to the ground. You can use the excitation editor to come up with a set of controls that makes your model squat, but it will require a lot of trial and error.

Best of luck,
Ajay

[Jicheng Xia]

Ajay,

Thanks for your reply. It's pretty helpful.

I did follow the tutorial 3, but the OpenSim always automatically closed without any warning when I did the inverse dynamics. I can't figure out the reason, so I switched to another computer, where it works very well.

Best regards,
Jicheng