Inverse Kinematics problem with full-body model

[Myroslav Bachynskyi]

Dear OpenSim users and developers,

I have collected full body motion capture data for arm movement. Now I'm trying to analyze this data with OpenSim software and SIMM full body model imported to OpenSim. I have created marker set that corresponds to our mocap laboratory setup. I scale model according to subject data from experiment. Next step I run Inverse Kinematics tool, and here comes problem. OpenSim hanged, without showing any progress or error. Later I left it working for hours and Inverse Kinematics tool stopped after 10 hours of running with some "Unknown error".

Than I thought that it could be problem with my data and to check, whether this is the case I tried to make OpenSim analysis of trc files from example Gait2354_Simbody. I tuned markers on full-body model to match markers from example, used same scale settings, as in example and same IK settings as in example. But when I start IK, it calculates something (i see high processor load) for couple of hours and throws same exception. I tried to modify scaling, disable part of degrees of freedom, run simulation on other computer, but without success. Problem can't be in data or settings, because with Gait2354 model everything works smoothly and fast.

Maybe you have some suggestions concerning cause of this problem? Has somebody seen similar behavior? Has somebody worked with SIMM full-body model in OpenSim? Are there some tricks?

I would appreciate any help or suggestions. Thank you in advance,

Myroslav

[Myroslav Bachynskyi]

Today Inverse Kinematics failed, but with some additional description of error:

Code: Select all

AssemblySolver::track() attempt Failed: SimTK Exception thrown at Assembler.cpp:887:
  Method Assembler::track() failed because:
Optimizer failed with message: SimTK Exception thrown at InteriorPointOptimizer.cpp:262:
  Optimizer failed: Ipopt: Restoration failed (status -2)
Assembly error tolerance achieved: 2.029626466892864e-015 required: 1e-006.
InverseKinematicsTool Failed: Unknown exception

And with this failure it also broke model into parts.

Have somebody comments about this?
Thank you.

[Ayman Habib]

Hi,

The likely reason for this is that some constraints could not be met so OpenSim couldn't put the model together again. I'd check the data you're trying to solve in the problematic frame to see if there's something wrong with it.

Please let us know how that goes,
-Ayman