Search found 506 matches

by Christopher Dembia
Tue Aug 25, 2020 11:44 am
Forum: OpenSim Moco
Topic: exempleSquattoSTand- Add external Load
Replies: 17
Views: 3660

Re: exempleSquattoSTand- Add external Load

Sorry, I should have been clearer. I was actually looking for a line higher up. Maybe you could just paste all of the optimizer output? I tried to reduce the convergence and constraint tolerance to 10e-2 and then 10e-1, the mesh interval to 10 and the maximum iterations number to 2000 but it failed ...
by Christopher Dembia
Mon Aug 24, 2020 10:22 am
Forum: OpenSim Moco
Topic: exempleSquattoSTand- Add external Load
Replies: 17
Views: 3660

Re: exempleSquattoSTand- Add external Load

This error might mean that your constraints can't be satisfied. For example, maybe the muscles are not strong enough.

Sometimes, however, we get this error for reasons we have not yet understood. Could you share the last few lines of output describing the iterations of IPOPT?
by Christopher Dembia
Fri Aug 21, 2020 9:45 am
Forum: OpenSim Moco
Topic: Four-bar mechanism
Replies: 5
Views: 1092

Re: Four-bar mechanism

Thanks for those details. I have created my own trc file indicating the position of the input bar at different instants of time (setting a constant angular velocity for the crank) and I want to obtain the velocity and acceleration position of the rest of the bars to check if I get the correct result...
by Christopher Dembia
Wed Aug 19, 2020 11:06 am
Forum: OpenSim Moco
Topic: Four-bar mechanism
Replies: 5
Views: 1092

Re: Four-bar mechanism

Dani, I'm curious: could you describe why you want to use MocoInverse (prescribing a given motion) rather than MocoStudy (predicting a new motion)? If you provided the motion, you may already know the accelerations. Where is the input motion from? You could do a prescribed-motion forward simulation ...
by Christopher Dembia
Wed Aug 19, 2020 10:21 am
Forum: OpenSim
Topic: Rolling On Surface Constraint
Replies: 2
Views: 1078

Re: Rolling On Surface Constraint

I would use ContactSpheres on the feet and a ContactHalfSpace for the ground. See this paper for an example of using OpenSim's Hunt-Crossley Force to model foot-ground contact: https://journals.plos.org/plosone/artic ... ne.0217730
by Christopher Dembia
Mon Aug 17, 2020 11:52 am
Forum: OpenSim Moco
Topic: Predict walking pattern by using OpenSim-Moco
Replies: 11
Views: 2171

Re: Predict walking pattern by using OpenSim-Moco

Carlos,

It's great to hear you got example2DWalking working in Python. Also, thank you for helping out on the forum. Would you be interested in contributing this back to the project? No pressure.

-Chris
by Christopher Dembia
Sun Aug 16, 2020 5:22 pm
Forum: OpenSim Moco
Topic: (close to) minimizing metabolic cost
Replies: 51
Views: 8910

Re: (close to) minimizing metabolic cost

Code: Select all

Is the 0.5 version fairly stable for the metabolics goal?
Yes, I think so.

Code: Select all

Or what are the plans for an official 0.5 release?
We are in the process of merging Moco into the `opensim-core` repository. We may delay the next release until that merging process is complete.
by Christopher Dembia
Sat Aug 15, 2020 10:31 pm
Forum: OpenSim Moco
Topic: (close to) minimizing metabolic cost
Replies: 51
Views: 8910

Re: (close to) minimizing metabolic cost

Karthick, you make a good point. There is currently no easy way to "clip"/"rectify" an output. Antoine Falisse contributed a metabolics model that can be used as a goal. It's not in an official release of Moco, but you should be able to try it out with this build (you might need to be logged into Gi...
by Christopher Dembia
Sun Aug 09, 2020 3:22 pm
Forum: OpenSim Moco
Topic: 3D walking with contact force
Replies: 3
Views: 756

Re: 3D walking with contact force

Are you able to use Moco 0.4.0? Please let us know if you continue to run into issues.

Note that we may still make small changes to Moco's interface in the coming months.
by Christopher Dembia
Sun Aug 09, 2020 3:21 pm
Forum: OpenSim Moco
Topic: Query related to UMocoD Project
Replies: 9
Views: 1844

Re: Query related to UMocoD Project

Karthick,

If coming by such data proves difficult, you can perform a sensitivity analysis to assess how much the fiber ratio affects your final results. It's possible that the fiber ratio has a small effect on your results.