Problems in FDK model

Main Forum
#1

Hi,

I am still using the AnyBody 6.0 version with the AMMR 1.6 to build my model. I have gotten some problems when i use the FDK model. I use patient-specific data to build the model. I have done nearly all the same as the TKA-kneebend demo but I still cant run the model. When I run the inverse dynamics, there is always an error "Failed to resolve force-dependent kinematics. Too small steps for GSS search causes looping of Newton method (final force error = 8.946040E+001). Continue anyhow..." comes up. When i look into the results, many muscle forces are around e-10N such as VastusLateralisInferior which is extremely large. And there are no contact forces in the tibial medial or lateral implant but the model actually penetrates the femoral component. Many thanks if you could help with my problem.

Regards,
Thomas

#2

Hi Thomas,

Please see this wiki section on how to trouble shoot FDK models.
All about Force Dependent Kinematics · AnyBody/support Wiki · GitHub

I would start by checking the surfaces.. in a separate model see All about Force Dependent Kinematics · AnyBody/support Wiki · GitHub

Please note there has been many improvements in both the body models and the software compare to the version you are using.

I hope the wiki page hints will help you move on

Best regards
Søren

#3

Hi,

Thanks Soren! I will check for it. The FDK model really has a lot of parameters to look into.

Regards,
Thomas