MB Knee: Multibody Models of the Human Knee Public Forum

[SimTK Admin]

Welcome to the MB Knee: Multibody Models of the Human Knee public forum. Feel free to browse or search the topics for helpful information, or post a topic of your own.

[Massimo Indietrolli]

Hi there, I am Max from University of Rome "Tor Vergata" Italy.

I found MBKnee a very interesting project, but I have a problem.

I am trying to run the MBKnee 3rd model, but it seems that ligament .dll file is missing.
I tried to use the 2nd model .dll but it seems that the simulation loops, taking a lot of time at 0% of CPU.

Can you help me? Can you provide the missing file?

Max

[Trent Guess]

Hi Max,

The ligament user subroutines are the same for all models. Either the 32 bit or 64 bit .dll should be in your ADAMS working directory.

-Trent

[Alexandria Mallinos]

Hi.
My name is Lexie and I am a doctoral student at Cleveland State University. When running the simulation for MBKnee_4, I keep getting this error and I am not sure how to fix it.

ERROR: Acceleration computation failed to converge after 25 iterations.
Equation with the largest imbalance: Vto/Frict/3 X Torque
Imbalance = 2.613031224E-02
Variable receiving largest increment: Part/2 X Acc
Delta = 0.000000000E+00
1) Check mass and inertia properties to ensure they are valid.
2) Make sure the choice of units is appropriate for the system.
Systems that have very small inertias may benefit from "small"
force units, e.g., dynes.
3) Check that motion generators are valid and no redundant constraints exist.
4) Check if impact functions caused a strange response in the model (verify properties).
5) An IMPLICIT DIFF element which does not reference DIF1 must be satisfied by its IC.
Simulation time is 1.094064193E-02
Simulation time is 1.094064193E-02
ERROR: Simulation failure detected.
ERROR: Simulation failure detected.

Thanks,
Lexie

[Trent Guess]

Hi Lexie, We ran these using the default solver settings in ADAMs 2013. You might try changing the solver settings. Otherwise, you may need to track down the part in the model that is causing the issue and make adjustments.

[Emma Martí]

Hello, i'm Emma, a bioengineering student.
I'm using this model for research, but i'm having some problems related to the ligament traking. On GUI there is no option to study the ligament lenght and forces, just the muscles. I would be very gratefull if someone could guide me and could tell me if there is some way to know this parameters.

Thank you very much,
Emma

[Saleh Mohazab-Rad]

Hello,
I am Saleh Mohazab, a student at QIET. I am trying to run the very same simulation on MBKnee_4 . I was wondering if the ligaments were made by adding spheres and springs together?
Thanks