I have also tried to add multiple types of springs instead of a ligament, but I end up with the same crash.

-Ryan

Has anybody been able to run Static Optimization with a ligament object in their model? I can run CMC just fine but SO does not run. The fact that CMC runs indicates to me that the ligament is implemented correctly.

Thank you
-Ryan Bakker

James,

Is the plotter able to plot ligament class properties as well?

-Ryan

Ajay, Thank you for your detailed post. It was very informative and helpful. I think I have a good grasp on it now. Does anybody know which method Sam used in his most recent paper "Muscle contributions to fore-aft and vertical body mass center accelerations over a range of running speeds"? I have d...

To give an example of the differences I am seeing, I have included two sets of figures. The first two figures are RRA pErr results. One with the "kinematics for external loads" and one without. The rest of the parameter files are exactly the same. The second set of figures are CMC reserve actuator r...

Hello, Could somebody please explain what “kinematics for external loads” in the GRF file does? The documentation (for ID) states “Next, you can specify the Kinematics for external loads file. In general, you should leave this blank. OpenSim will then use the specified kinematics that are being trac...

Ajay Thank you for taking the time to write a detailed response, it was very helpful and informative. I want to confirm that I understand the end consequence correctly. “Unfortunately, the effective torque experienced by the knee joint are very different”. Ultimately, because the 2392 model has a la...

Hello I am using the Gait 2392 model to calculate muscle forces required to perform various gait activities. I apply calculated CMC muscle forces to cadaveric knee specimens and record the ACL strain. In order to apply these muscle forces to my specimen I must first correct for the moment arm differ...

I may be wrong because I do not normally use Forward Dynamics but I do believe you need to also include your GRF forces in order to achieve the tracked kinematics. Otherwise the simulation will fall through the floor.

Let me know if this helps

Fabian How does your scaling and inverse kinematics look? Are they giving satisfactory results? Have you tried running inverse dynamics? Do the values look reasonable for the motion you are studying? The source of your error could be from an incorrect scale, poor IK or incorrectly applied GRF. In my...